"Smarter Timing Solutions"

Meridian II Precision TimeBase
GPS-SynchronizedUser Manual

USM3043-0000-000 Revision 10
September 2021

Meridian II GPS

Precision TimeBase User Manual
PrefaceThank you for purchasing the Meridian II Precision TimeBase. Our goal in developing this productis to provide an extremely accurate time and frequency standard referenced to Coordinated Universal
Time (UTC) that you can deploy quickly, easily and reliably. Your new Meridian II is fabricated using the highest quality materials and manufacturing processes available today, and will give you yearsof troublefree service.

About EndRun Technologies

EndRun Technologies has been dedicated to the development and refinement of the technologies
required to fulfill the demanding needs of the time and frequency community since 1998.
The instruments produced by EndRun Technologies have been selected as the time and frequency
reference for such rigorous applications as enterprise computer synchronization, research institutions,aerospace, network quality-of-service monitoring, satellite earth stations, and calibration laboratories.

Trademark Acknowledgements

Linux, UNIX, and Windows are registered trademarks of the respective holders.

EndRun Contact Information
Address:

Phone:
Fax:
Sales:
Support:EndRun Technologies
2270 Northpoint Parkway
Santa Rosa, CA 95407
U.S.A.
(707)573-8633(707)573-8619
1-877-749-3878 or (707)573-8633
sales@endruntechnologies.com
1-877-749-3878 or (707)573-8633
support@endruntechnologies.com

Part No. USM3043-0000-000 Revision 10
September 2021
Copyright © EndRun Technologies 2015-2021
Meridian II User ManualAbout This ManualThis manual will guide you through simple installation and set up procedures.
Introduction – The Meridian II, how it works, where to use it, its main features.
Basic Installation – How to connect, configure and test your Meridian II with your network.
NTP Server and Client Set-Up – Two client sections; one for Unix-like platforms and one for Windows.
Network Protocols - Covers Security, SNMP, HTTPS, IPv6 and PTP/IEEE-1588.
Console Port – Description of the console commands for use over the network and serial ports.
Front-Panel Keypad and Display – How to operate the user interface that provides convenient setup andmonitoring of the instrument.
Options – Description of any optional features that your Meridian II might have.
If you detect any inaccuracies or omissions, please inform us. EndRun Technologies cannot be held
responsible for any technical or typographical errors and reserves the right to make changes to the
product and manuals without prior notice.

Warranty

This product, manufactured by EndRun Technologies, is warranted against defects in material andTworkmanship for a period of two years from date of shipment, under normal use and service. During the warranty period, EndRun will repair or replace, at its option, products which prove to be defective. Products not manufactured by EndRun Technologies are warranted for ninety days or longer,
as provided by the original equipment manufacturer, from date of shipment.

Extended Warranty

EndRun products are supported by a strong, comprehensive standard warranty (see paragraph above).
Extended warranties are available to expand the coverage period. The extended warranty can bepurchased at the time of order, or during the last year of the standard warranty period.

Limitation of Warranty

The foregoing express warranty shall not apply to defects resulting from improper or inadequate
maintenance by Buyer or User, Buyer-supplied software or interfacing, unauthorized modification or
misuse, operation outside of the environmental specifications for the product, or improper site preparation or maintenance.
TO THE EXTENT PERMITTED BY LAW, THIS WARRANTY AND REMEDIES SET FORTHABOVE ARE EXCLUSIVE AND IN LIEU OF ALL OTHER WARRANTIES, REMEDIES AND
CONDITIONS, WHETHER ORAL OR WRITTEN, STATUTORY, EXPRESS, OR IMPLIED. AS
PERMITTED BY APPLICABLE LAW, ENDRUN SPECIFICALLY DISCLAIMS THE IMPLIEDWARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Meridian II User ManualWarranty Repair

If you believe your equipment is in need of repair, contact EndRun Customer Support. It is important
to contact us first as many problems may be resolved by phone or email. Please provide the serial
number of the unit and the nature of the problem. If it is determined that your equipment will require
service, we will issue an RMA number and specific shipping instructions.
Ship the unit prepaid in the original container or a container of sufficient strength and protection
to EndRun Technologies. EndRun will not be responsible for damage incurred during shipment tous. Buyer shall prepay shipping charges to send product to EndRun and EndRun shall pay shipping
charges to return product to Buyer. However, if returned product proves to be operating normally(not defective) then Buyer shall pay for all shipping charges. If Buyer is located outside the U.S.A.
then Buyer shall pay all duties and taxes, if any.
Be sure the RMA number is clearly identified on the outside of the shipping container. Our policy
is to repair the unit within 5 business days. If it is necessary to order parts or if other circumstancesarise that require more than 5 days, an EndRun service technician will contact you.
Loaner units are not included as part of the standard warranty.

Repair After Warranty Expiration

If the warranty period has expired, we offer repair services for equipment you have purchased from
EndRun. Contact EndRun Customer Support. It is important to contact us first as many problems
may be resolved by phone or email. Please provide the serial number of the unit and the nature of
the problem. If it is determined that the equipment has failed and you want EndRun to perform therepairs, we will issue you an RMA number and specific shipping instructions.
Ship the unit prepaid in the original container or a container of sufficient strength and protection to
EndRun Technologies. EndRun will not be responsible for damage incurred during shipment to us.
Customer is responsible for shipping costs to and from EndRun Technologies. Be sure the RMA
number is clearly identified on the outside of the shipping container. After the equipment has been
received we will evaluate the nature of the problem and contact you with the cost to repair (parts andlabor) and an estimate of the time necessary to complete the work.

Limitation of Liability

The remedies provided herein are Buyer’s sole and exclusive remedies. EndRun Technologies shallnot be liable for any direct, indirect, special, incidental or consequential damages, whether based oncontract, tort or any other legal theory.

Meridian II User ManualTable of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
About EndRun Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Trademark Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
EndRun Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Extended Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Limitation of Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Warranty Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Repair After Warranty Expiration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Limitation of Liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Chapter One - Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Robust GPS Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Highly-Reliable, Modular Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Standard Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Secure Network Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Free FLASH Upgrades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Time Synchronization Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
GPS Timing-How It Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Where to Use It . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Client/Slave Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Chapter Two - Basic Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Checking and Identifying the Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Meridian II Physical Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Performing a Site Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Installing the Meridian II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Connecting the Optional DC Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Connecting and Configuring Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Meridian II User ManualConfiguring Ethernet with the Front-Panel Keypad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Connect the RS-232 Serial I/O Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Test the Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Using netconfig to Set Up Your IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Verify Network Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Check Network Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Using Telnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Using SSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Using HTTPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Connecting Instruments to the Meridian II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Configuring Ethernet with the Serial Port

Chapter Three - Console Port Control and Status . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Console Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
General Linux Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Available User Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Detailed Command Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
accessconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
antfltmask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
caldelay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
clearalmanac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
cpuio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
cpuioconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
cpustat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
dumpalmanac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
dumpephemeris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
faultstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
get_sw_opts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
gpsdynmode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
gpsionoinfo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
gpslastfix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
gpsrefpos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
gpsrefpos_ecef . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
gpsstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Meridian II User Manualgpstrkstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
gpsutcinfo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
gpsversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
inetdconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
inhibitoutputsmode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
installed_sw_opts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
ionostat (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
kernelversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
kplockstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
lockoutkp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
logrinex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
netconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
ntpconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
ntpstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
oscctrlstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
passwd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
pluginopts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
pluginoptsconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
ptpconfig0 and ptpconfig1 (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
ptpstat0 and ptpstat1 (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
pwrfltmask (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
rcvrserialnumber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
rcvrstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
rcvrversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
resetlastgpswn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
resetleaphistory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
rticmode (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
serialnumber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
setantfltmask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
setcaldelay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
setgpsdynmode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
hp5071astat

Meridian II User Manualsetgpsrefpos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
setinhibitoutputsmode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
setrticmode (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
setsigfltmask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
settfomfltlvl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
sigfltmask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
subsysreset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
sysosctype . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
sysrootfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
sysstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
systemio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
systemioconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
systimemode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
systimemodeconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
sysversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
tfomfltlvl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
triggerppo (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
unlockkp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
updatekernelflag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
updaterootflag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
upgradekernel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
upgradercvr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
upgradercvrfpga . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
upgraderootfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
upgradesubsys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
wrt_sw_opt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
syskernel

Chapter Four - Hyper Text Transfer Protocol Secure (HTTPS) . . . . . . . . . . . . . . . 47
HTTPS Interface Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Page Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Home: Overall Status Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Home: Front Panel Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Meridian II User ManualHome: User Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Home: Logout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Plots Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Receiver: Receiver Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Receiver: Oscillator Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
I/O Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
I/O Page (Plug-In Options) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Faults: System Faults Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Faults: Fault Mask Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Faults: TFOM Fault Level Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Faults: Receiver Faults Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Network: IPv4 Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Network: IPv6 Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Network: DNS Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Network: MAC Address Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
NTP Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
PTP: Status and Configuration Pages (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Firmware: Firmware Status Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Firmware: Linux RFS Upgrade Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Firmware: Linux Kernel Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Firmware: GPS Subsystem Upgrade Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Firmware: GPS Receiver Upgrade Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Firmware: Reboot Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Disable or Restrict Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Clock Page

Chapter Five - Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Linux Operating System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Restrict Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Restrict Access - Telnet, SSH and SNMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Restrict Access - HTTPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Restrict Query Access - NTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Disable Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Disable Telnet, Time and Daytime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Meridian II User ManualDisable SNMP, SSH and HTTPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Is the Protocol Disabled? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
OpenSSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Configure Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
HTTPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Configure Certificate and Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
NTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Network Security Vulnerabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Re-Enable SNMP, SSH and HTTPS

Chapter Six - Simple Network Management Protocol (SNMP) . . . . . . . . . . . . . . 67
SNMPv3 Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Enterprise Management Information Base (MIB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Invocation of the SNMP daemon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Quick Start Configuration -- SNMPv1/v2c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Change Default Community Strings (Passwords) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Configuring SNMPv1 Trap Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Configuring SNMPv2c Notifications and Informs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Configuration of SNMPv3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Configuring SNMPv3 Notifications and Informs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Example of usmUser Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Disable or Restrict Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Chapter Seven - Network Time Protocol (NTP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Configuring the NTP Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Configuring the Meridian II as a Stratum 1 Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Configuring NTP Using the Front-Panel Keypad/Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Configuring NTP Using the Network Interface or Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Configuring the Meridian II as a Stratum 2 Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Edit ntp.conf File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Mask Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Setting Up NTP Clients on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Unix-like Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Unix-like Platforms: Basic NTP Client Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Meridian II User ManualConfigure NTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Unix-like Platforms: MD5 Authenticated NTP Client Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Configure NTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Unix-like Platforms: Broadcast/Multicast NTP Client Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Configure NTP Client for Broadcast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Configure NTP Client for Multicast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Test Broadcast/Multicast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Setting Up NTP Clients on Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Windows: W32Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Create the ntp.keys File

Chapter Eight - IPv6 Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
IPv6 Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
OpenSSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Apache HTTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Net-SNMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
NTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
IPv4-Only Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Chapter Nine - Optional Precision Time Protocol (PTP/IEEE-1588) . . . . . . . . . . 87
Software Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
About PTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Two Gigabit Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
PTP Configuration and Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Default PTP Configuration Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
PTP Configuration and Status Using the Keypad/Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
PTP Configuration Using the Network or Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
PTP Status Using the Network or Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
PTP Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
About the PTP Second and UTC Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
PTP Second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
UTC Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Multiport PTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Meridian II User ManualDisable the PTP Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Re-Enable PTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Chapter Ten - Rear-Panel Inputs/Outputs (I/O) . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Standard I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Antenna Jack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Ethernet Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Serial I/O Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
1 PPS Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
View the 1 PPS Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Change the 1 PPS Pulse Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Time Code Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
View the Time Code Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Change the Time Code Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
CPU Module Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Programmable Pulse Output (PPO) Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
View and Change the PPO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Trigger PPO Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Direct Digital Synthesizer (DDS) Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
View the DDS Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Change the DDS Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
10 MPPS Output Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
View the 10 MPPS Output Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Alarm Output Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
View the Alarm Output Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Serial Time Output Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
View the Serial Time Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Change the Serial Time Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Sysplex Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Truetime Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
EndRun Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
EndRunX (Extended) Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
NENA Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
NMEA Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Meridian II User ManualPlug-In Module Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
View the Plug-in Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Change the Plug-in Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Digital Output Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Digital Output Module - Programmable Pulse Output (PPO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Digital Output Module - Direct Digital Synthesizer (DDS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Digital Output Module - 1 PPS or 10 MPPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Analog Time Code Output Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Low Phase Noise (LPN) Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Sine Wave Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Direct Digital Synthesizer (DDS) Sine Wave Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Telecom Clock Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
User Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Connectors and Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
5071A Cesium Control Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Cesium Status Using the Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Power Supply Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
DC Power Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Connecting the DC Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Dual-Redundant Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Masking Dual Power Supply Fault Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Digital Output Module - Time Code

Chapter Eleven - Real-Time Ionospheric Corrections (RTIC) Option . . . . . . . . . . 131
Software Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
About RTIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Ionospheric Delay and Impact To GPS Time-Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Our Proprietary Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Performance Verified at National Institute of Standards and Technology (NIST) . . . . . . . . . . . . . . . . . . . . . 133
Meridian II User ManualRTIC Configuration and Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
RTIC Configuration and Status Using the Network or Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
ionostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
rticmode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
setrticmode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
RTIC Performance Plots Using the HTTP Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
RTIC Stability Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
RTIC Configuration and Status Using the Keypad/Display

Chapter Twelve - Optional Synchronous Ethernet (SyncE) . . . . . . . . . . . . . . . . . . 137
Software Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
About SyncE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Disable the SyncE Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Re-Enable SyncE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Chapter Thirteen - Front-Panel Keypad and Display . . . . . . . . . . . . . . . . . . . . . . . 141
Display Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Keypad Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Display and Keypad Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Traversing the Display Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Editing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Keypad EDIT Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Using Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Shortcut Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Detailed Display Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Time/Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Main Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
CPU Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Receiver Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Receiver: Status (GPS Subsystem/Receiver Status) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Receiver: Satellite Vehicle Information (SV_Info) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Receiver: Reference Position (Ref_Pos) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Meridian II User Manual

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Receiver: UTC Information (UTC_Info) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Receiver: Dynamic Mode (Dyn_Mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Receiver: Oscillator Status (Osc_Stat) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Receiver: Calibrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Receiver: RTIC (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Faults Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Faults: System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Faults: Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Faults: Antenna Fault Mask (AntFltMask) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Faults: Signal Loss Fault Mask (SigFltMask) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
TFOM Fault Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Faults: Dual Power Input Fault Alarm Masks (PwrFltMask) (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
I/O Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
System I/O Menu (Sys_I/O) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
CPU Module I/O Menu (CPU_I/O) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Network Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Network: Network4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Network: Network6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Network: MAC Address (MAC_Addr) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Network: REBOOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
NTP Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
NTP: Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
NTP: I/O Statistics (I/O_Stats) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
NTP: Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
PTP Menu (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Clock Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Clock: Time Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Clock: Time Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Clock: Hour Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Clock: Daylight Saving Time (DST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Display Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
About . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Receiver: Last Fix Position (Last_Fix)

Meridian II User ManualAppendix A - Time Figure of Merit (TFOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Appendix B - Upgrading the Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Upgrade via the HTTPS Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Upgrade via the Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Performing the Linux RFS Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Transfer File to Meridian II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Recovering from a Failed RFS Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Performing the Linux Kernel Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Transfer File to Meridian II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Recovering from a Failed Kernel Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Performing the GPS Subsystem Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Problems with the GPS Subsystem Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Performing the GPS Receiver Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Problems with the GPS Receiver Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Performing the GPS Receiver FPGA Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Appendix C - Helpful Linux Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Linux Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Linux Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Detailed Information Is Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Change Password . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
List Active Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
NTP Monitoring and Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Text Editors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Change Log-In Banners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Query and Change Ethernet Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Redirect Syslog Files to Remote Host . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Appendix D - Third-Party Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
GNU General Public License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
NTP Software License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Apache Software License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
PTP Software License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Meridian II User ManualAppendix E - Installing the GPS Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Antenna Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
GPS Antenna Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
About Coax Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Long Cable Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Recommended Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Using GPS Low-Noise Amplifiers (LNAs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Using Two or Three LNAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Other Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Lightning Arrestor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Signal Splitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Calibrate Your Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Mounting On A Rooftop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Obtaining A Reference Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
About WGS-84 Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Appendix F - Leap Seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Automatic Leap Second Insertion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Background Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Appendix G - System Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Masking Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
System Fault Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Receiver Fault Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Appendix H - Time Code Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
IRIG-B122/002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
IRIG-B123/003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
IRIG-B120/000 (IEEE-Standard 1344-1995) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
NASA-36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
2137 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
IEEE-1344 Bit Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Appendix I - Software Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Meridian II User Manualwrt_sw_opt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
installed_sw_opts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
get_sw_opts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Software Option Bit Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

Appendix J - Operation with a GPS Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Console Port Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
clearalmanac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
resetlastgpswn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
resetleaphistory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Appendix K - Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Software Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
System Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Power Supply Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
CPU Module Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
Plug-In Module Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Special Modifications - Changes for Customer Requirements . . . . . . . . . . . . . . . 217

Meridian II User ManualThis page intentionally left blank.

Meridian II User Manual

"Smarter Timing Solutions"

Chapter One
Introduction

The Meridian II Precision TimeBase is a high-performance, full-featured system that provides highlyprecise time and frequency outputs. The modular design allows for easy, field-installed upgrades thatcan satisfy virtually any time and frequency requirement. Advanced packaging techniques, coupledwith compact card design, allow for the installation of up to five option boards in a single 1U or 2U
chassis.
Using a proprietary Global Positioning System (GPS) timing receiver, the Meridian II supports
operation in static or dynamic (shipboard only) platforms. Proprietary multiple satellite optimalensembling, adaptive 3rd order frequency control and TRAIM algorithms maximize the accuracy,
stability, and reliability of the output signals. A variety of top-quality quartz and rubidium oscillators
are available to handle the full range of holdover, phase noise, and short-term stability requirements.
Units equipped with our Ultra-Stable OCXO provide unmatched close-in phase noise performanceand short-term stability.
The Meridian II uses GPS transmissions to precisely synchronize its clock within 10 nanoseconds of
Coordinated Universal Time (UTC). The frequency of the internal oscillator is disciplined to match
the frequency of the UTC timescale to less than 1 part in 1013 over 24-hour observation intervals.
The time and frequency outputs are coherent after initial GPS synchronization and maintained via
20-bit DAC frequency control, rather than phase stepping, to provide excellent short-term stability.
For more detailed information that is not included in this manual, and links to other sites, please visit
our website: endruntechnologies.com. There you can also download firmware upgrades, the latest
manuals and other documentation.

Main Features

Robust GPS Receiver
Meridian II is a GPS-based time and frequency standard designed to support mission critical applications. The proprietary GPS timing receiver in Meridian II has many safeguards to protect against
false GPS signals. The receiver strictly adheres to the GPS Interface Specification and performs
low-level integrity checks to protect against weak corrupted signals, jamming, spoofing and accidental GPS control system errors. EndRun’s GPS timing receiver technology has evolved to be highlyrobust against these threats to provide time and frequency outputs you can trust.
Highly-Reliable, Modular Design
The Meridian II provides high performance and reliability combined with low power consumption
and cost. Its internal sub-assemblies are fabricated using state-of-the-art components and processes
and are integrated in a solid, high-quality chassis. Since it uses highly efficient ARM microproces1

Meridian II User ManualCHAPTER ONE

sors, the Meridian II is convection-cooled and the chassis is sealed to eliminate the maintenance andreliability issues associated with fan-cooled architectures. Air currents flowing over sensitive frequency control components are also eliminated so that the extraordinary short-term stability available
from the Meridian II oscillators is preserved. A complete suite of time and frequency capabilities
with an exceptionally high number and variety of outputs are provided in a 1U or 2U, 19” rackmountable chassis. The modular, plug-and-play design of the Meridian II and a wide range of option
cards make it easy to tailor the unit to support your applications.
Standard Features
In addition to sourcing a precision 1 PPS timing reference and an IRIG-B time code output, your Meridian II includes dual gigabit Ethernet ports with a high-bandwidth Network Time Protocol (NTP)
server. The Meridian II incorporates a vibrant, high density, dot-matrix, vacuum-fluorescent display
and a user-friendly keypad design for control and status monitoring. The Meridian II can also be
managed via the network port or a local console on the RS-232 serial port. See Chapter 13 - FrontPanel Display and Keypad, Chapter 3 - Control and Status Commands, and Chapter 7 - NTP for
more information.
Secure Network Interface
Dual 10/100/1000Base-T Ethernet ports are provided as a standard feature of the Meridian II with awide variety of protocols including NTP, SNMP with Enterprise MIB, SSH, Telnet, FTP, HTTPS,
and SNTP. Refer to Chapter 2 - Basic Installation for information to help you set up your network
interface. The inclusion of SNMP v3 and SSH provides a very secure network interface and allows
you to safely perform monitoring and maintenance activities over the network. Security-conscious
users can also disable any or all of the risky protocols such as HTTPS, Telnet, Time and Daytime. In
addition, access via SSH, SNMP and Telnet can be restricted to specific hosts. Refer to Chapter 6- SNMP and Chapter 5 - Security for further information.
Free FLASH Upgrades
Firmware and configurable hardware parameters are stored in non-volatile FLASH memory, so the
Meridian II can be easily and securely upgraded in the field using SSH and SCP or the local RS-232
serial port. Upgrades via FTP and Telnet are also possible although these protocols are not secure.
We make all firmware upgrades to our products available to our customers free of charge. For firmware upgrade procedures refer to Appendix B - Upgrading the Firmware.

Time Synchronization
Components

The Meridian II contains a GPS Subsystem composed of EndRun Technologies’ proprietary GPS Receiver and a system quartz or Rubidium oscillator. All quartz oven controlled oscillators are EndRun
Technologies’ proprietary design as well, and provide state-of-the-art close-in phase noise and shortterm stability. The GPS Subsystem is integrated with a fanless, convection-cooled high performance
ARM CPU with two integrated Ethernet ports that provide NTP (and optionally IEEE 1588/PTP).
This is called the Linux/NTP Subsystem. Figure 1 shows Meridian II’s time synchronization components.

2

Meridian II User ManualGPS Receiver Subsystem
GPS Receiver Module

ReceiverOscillator
PLL

Receiver
Processor

1PPS

ReceiverSubsystem
Processor
1PPS

10MHz

10MHz

EFC

SystemOscillator

10MHz

Linux NTP/PTP Subsystem

FIGURE 1 - MERDIAN II GPS SYSTEM TIMEBASEGPS Timing-How It Works

The time and frequency engine in the Meridian II receives transmissions from satellites that are operating in compliance with the Navstar GPS Interface Specification known as IS-GPS-200. It specifies
the receiver interface needed to receive and demodulate the navigation and time transfer data contained in the GPS satellite transmissions. The GPS navigation system requires a means of synchronizing the satellite transmissions throughout the constellation so that accurate receiver-to-satellite
range measurements can be performed via time-of-arrival measurements made at the receiver. For
the purposes of locating the receiver, measurements of the times-of-arrival of transmissions from atleast four satellites are needed for maximum timing accuracy. Time transfer to a receiver at a known
position from a single satellite is supported,
The GPS system designers defined system time to be GPS time. GPS time is a monotonic time scaleconsisting of an ensemble of high-performance cesium beam and rubidium vapor atomic frequency
standards located in the monitoring stations and satellites. GPS time is measured relative to UTC,
as maintained by the United States Naval Observatory (USNO), and maintained synchronous with
UTC(USNO) except that it does not suffer from the periodic insertion of leap seconds. Such discontinuities would unnecessarily complicate the system’s navigation mission. Contained in the datatransmitted from each satellite is the current offset between GPS time and UTC(USNO). This offset
is composed of the current integer number of leap seconds difference and a small residual error that is
typically less than +/- 10 nanoseconds.
Each satellite in the constellation contains redundant cesium beam or rubidium vapor atomic frequency standards. These provide the timebase for all transmissions from each satellite. These transmissions are monitored from ground stations located around the world and carefully measured relative to
GPS time. The results of these measurements for each satellite (i.e. correction to GPS time) are thenuploaded to that satellite so that they may be incorporated into the data contained in its transmissions.
The receiver can use this data to relate the time-of-arrival of the received transmissions from thatsatellite to GPS time and by using the transmitted UTC parameters, to UTC(USNO).
3

Meridian II User ManualCHAPTER ONE

All of this means that during normal operation, the source of the timing information being transmitted
from each of the satellites is directly traceable to UTC(USNO). Due to the nature of the GPS spread
spectrum Code Division Multiple Access (CDMA) modulation scheme, this timing information may
be extracted by a well-designed receiver with a precision of a few nanoseconds. The GPS time andfrequency engine in the Meridian II does just that.

Where to Use It

Client/Slave Software

Since signals from the GPS satellites are available at all locations on the globe, you may deploy the
Meridian II virtually anywhere. However, you must be able to install an antenna with good sky visibility, preferably on the rooftop.

Meridian II has been designed to operate in conjunction with existing public domain NTP/SNTP client software and may be used in any network environment that is using TCP/IP protocols. Althoughclient software is available for all platforms, for the most precise applications, the Unix-like operating
systems are best supported. For more information see Chapter 7 - NTP, Setting Up NTP Clients on
Unix-like Platforms and Setting Up NTP Clients on Windows. There is additional information about
NTP Client software at this link:endruntechnologies.com/products/ntp-time-servers/ntp-client-software
For PTP/IEEE-1588 applications, the Meridian II can interoperate with a variety of Slave softwareand hardware. For more information on PTP Slave Software go to this link:endruntechnologies.com/products/grandmaster-clocks/ptp-slaves

4

Meridian II User Manual

"Smarter Timing Solutions"

Chapter Two
Basic Installation

This chapter will guide you through the most basic checkout and physical installation of your Meridian II Precision TimeBase. See Chapter 7 - NTP for instructions on how to configure your unit as an
NTP Server. See Chapter 9 - PTP/IEEE-1588 for instructions on how to configure your unit as an
optional PTP Grandmaster. Other chapters and appendices will give you the information needed toconfigure your installation for the maximum performance in your operating environment.
Basic familiarity with TCP/IP networking protocols like ping, telnet and ftp is required. Thoughsome familiarity with Linux or other Unix-like operating systems would be helpful, it is not essential. If you satisfy these conditions, the instructions provided herein should guide you to a successful
installation. For a brief description of some helpful Linux commands and utilities see Appendix C- Helpful Linux Information.

Checking and Identifying
the Hardware

Unpack and check all the items using the shipment packing list. Contact the factory if anything is
missing or damaged. The Meridian II Precision TimeBase shipment typically contains:• Meridian II 1U (part #3043-xxxx-xxx (1U) or #3045-xxxx-xxx (2U))• Meridian II User Manual (part #USM3043-0000-000) on CD (part #5102-0001-000)• IEC 320 AC Power Cord (part #0501-0003-000)(This part will not be present if using the DC power option.)• DB9F-to-DB9F Null-Modem Serial I/O Cable (part #0501-0002-000)• RJ-45 to RJ-45 CAT-5 patch cable, 2 meters (part #0501-0000-000)• Antenna/cable assembly (part #0610-0009-001 or #0610- variant)5

Meridian II User ManualCHAPTER TWO

Meridian II PhysicalDescription

The front-panel drawing below shows the 1U version of the Meridian II. There is also a 2U chassis
available.
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Sync LED

This amber LED flashes to indicate synchronization status.

Alarm LED

This red LED illuminates briefly at power-up, and thereafter whenevera serious fault condition exists.
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���� �������� �� � �� ����������� � �� � ������������� ��� �� ��������

The drawings above show the Meridian II rear-panel with all five option card slots filled. Both the
1U chassis and 2U chassis are shown. There are a wide variety of option modules and various outputs available. For more information see Chapter 10 - Rear-Panel I/O. (For a dimensional drawingof the Meridian II chassis see Appendix K - Specifications.) Descriptions below briefly describe thestandard and optional I/O connectors:
GPS Antenna Input

This TNC connector mates with the downlead cable from the externalantenna.

RS-232 PortThis DB9M connector provides the RS-232 serial I/O console
interface to the Meridian II. This console allows you to initialize
and maintain the Meridian II. See Chapter 3 - Console Port Control
and Status for more information and Appendix K - Specifications for
the RS-232 pin assignments.

10/100/1000Base-T Jacks

These two RJ-45 connectors mate with the Ethernet twisted pair cablefrom the network. They are labeled “ETH0” and “ETH1” with the cor
responding MAC address. Integrated LEDs indicate link speed (green)
and activity (amber). Both ports provide a console interface to the
Meridian II. See Chapter 3 - Console Port Control and Status formore information.

6

Meridian II User ManualB A S I C I N S TA L L AT I O N

1 PPS Output

This BNC connector provides the 1 PPS TTL output. The pulse widthis normally 1 millisecond wide when shipped from the factory but canbe changed via the front-panel keypad or via console command
cpuoptsconfig. Other selections are 20 microseconds, 100
milliseconds and 500 milliseconds. See signal definition in
Appendix K - Specifications for the 1 PPS Output.

AM Code Output(Time Code)This BNC connector provides the amplitude-modulated time code
output. The time code output is normally IRIG-B122 when shippedfrom the factory, but can be changed via the front-panel keypad or via
console command cpuoptsconfig. Other selections are available.
See signal definition in Appendix K - Specifications for the AM Code
Output.

Alarm Output(Option)This BNC connector (or terminal strip) provides the optional alarm
output, and is usually not installed. If installed, see description in
Chapter 10 - Rear-Panel I/O and signal definition in Appendix K Specifications.

Programmable Pulse Output This BNC connector provides the optional Programmable TTL pulse(Option)rate output and is usually not installed. If installed, see description
in Chapter 10 - Rear-Panel I/O and signal definition in Appendix K Specifications.

7

Digital Code Output(Option)This BNC connector provides the optional digital (DC-Shift) timecode output. The format matches the format selected for the AM Code
Output. See signal definition in Appendix K - Specifications for the
Digital Code Output.

DDS Output(Option)This BNC connector provides the optional Direct Digital Synthesizer(DDS) output and is usually not installed. If installed, see description
in Chapter 10 - Rear-Panel I/O and signal definition in Appendix K Specifications.

10 MPPS Output(Option)This BNC connector provides an optional 10 MPPS rate output
and is usually not installed. If installed, see description in
Chapter 10 - Rear-Panel I/O and signal definition in Appendix K Specifications.

1 PPS RS-422 Output(Option)This optional DB-9M connector provides the 1 PPS output at RS-422
levels and is usually not installed.. The pulse width is normally
1 millisecond wide when shipped from the factory but can be changed
via the front-panel keypad or via command cpuoptsconfig. See
pinout details in Appendix K - Specifications for the 1 PPS RS-422
Output.

Serial Time Output(Option)This optional DB-9M connector provides the serial I/Ointerface with a once-per-second ASCII time string output and is

Meridian II User ManualCHAPTER TWO

usually not installed. For further information refer see description
in Chapter 10 - Rear-Panel I/O and Appendix K - Specifications.
Spare Outputs(Unused)

These unused BNC connectors are usually labeled “SPARE”. Whenused, they will be labeled with their connector identifier (A, B, or C)
and provide optional signals. Label examples are: “A-AMCODE”,“B-1 PPS”, or “C-PPO”. For more information on Meridian II
options see Chapter 10 - Rear-Panel I/O.

Plug-In Modules(Options)Your Meridian II has five option slots that can be configured with avariety of plug-in modules. See Chapter 10 - Rear-Panel I/O for
detailed information on the various modules.

AC Power Input JackThis IEC 320 standard three-prong connector provides AC power.
Optional DC and dual AC power supplies are also available. See
Chapter 10 - Rear-Panel I/O and Appendix K - Specifications formore information.

DC Power Input Block(Option)This optional 3-position terminal block provides connection to the
DC power source, and replaces the AC power input jack. See details
in Chapter 10 - Rear-Panel I/O and Appendix K - Specifications.

�

Dual Power Supplies(Option)

Performing a
Site Survey

�This option provides an additional power supply, which is permanently
installed in two of the option slots. The two power supplies, may be
any combination of AC-input or DC-input power options, are notfield-swappable. Power Supply A (primary) and Power Supply B(secondary) are connected in a dual-redundant configuration with hit
less automatic A-to-B and B-to-A switchover. The chassis is sourced
from Power Supply A as long as it is operational and is suppliedwith external power.

Using the front panel status LED indicators, it’s easy to find out if your Meridian II will work in yourdesired location:
1.Temporarily mount the antenna on the roof. Make sure that it is not blocked by large metallic objects closer than one meter. See Appendix E - Installing the GPS Antenna for more information.
2. Screw the TNC plug on the end of the antenna cable onto the TNC antenna input jack on the chassis rear panel of the Meridian II.
3. Apply power.

8

Meridian II User ManualB A S I C I N S TA L L AT I O N

Initially upon power up:
1. The unit will light the Alarm LED for about 10 seconds.
2. Then it will continuously light the Sync LED.
3. When the unit locks onto a GPS signal and begins to decode the timing data and adjust the systemoscillator, the Sync LED will flash very rapidly (about a 6 Hz rate) until the data is fully decoded andthe system oscillator is fully locked to the GPS frequency.
4. Then the Sync LED will pulse at precisely a 1 Hz rate, synchronized to UTC seconds.

NOTE
If your unit has an OCXO (MS-OCXO, HS-OCXO, US-OCXO) or rubidum (Rb, US-Rb) oscillator then it will
require a 5-10 minute warm-up period before it begins searching for a GPS signal.
At this point, the GPS Subsystem is fully synchronized, and you may proceed to permanently mountthe chassis and antenna in their desired locations. If you are unable to achieve GPS lock after 24hours, then contact EndRun Customer Support for assistance.

NOTE
In order for the Meridian II to synchronize with maximum accuracy to UTC, the delay for the cable and all
devices between the antenna and the GPS receiver must be compensated. See Appendix E - Installing
the GPS Antenna, Calibrate Your Receiver for more information.

Installing the Meridian II
FCC NOTICEThis equipment has been tested and found to comply with the limits for a Class A digital device, pursuant
to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmfulinterference when the equipment is operated in a commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a
residential area is likely to cause harmul interference in which case the user will be required to correct theinterference at his own expense.
Using standard 19” rack mounting hardware, mount the unit in the desired location. After mounting
the unit and connecting the antenna cable, verify that it still acquires and tracks a GPS signal.

9

Meridian II User ManualCHAPTER TWO

CAUTION
Ground the unit properly with the supplied power cord.
The socket outlet should be installed near the equipment and be easily accessible.
Power cord is used as a disconnection device. To de-energize equipment, disconnect the power cord. If
your Meridian II has dual power supplies, then multiple power cords may be installed. To de-energize thisequipment, disconnect all power cords from the device.
Do not install the Meridian II where the operating ambient temperature might exceed 122°F (50°C).

Connecting the Optional DC PowerThe DC Power Input is an option. For installation instructions see Chapter 10 - Rear-Panel I/O,
Connecting the DC Power.

Connecting and Configuring Ethernet

Connect one end of the CAT-5 patch cable supplied with your Meridian II to either of the rear panel
mounted RJ-45 connectors labeled 10/100/1000BASE-T. Connect the other end of the patch cable toyour network through a ‘straight’ port on your switch. Do not connect it to a ‘crossover’ port on yourswitch.
By factory default, the Meridian II will attempt to configure the Ethernet interfaces automatically via
the Dynamic Host Configuration Protocol (DHCP). The Meridian II will attempt to set the netmask,
its IP address, the IP address of the default gateway, the domain name and the IP addresses of any
nameservers, if the DHCP server is configured to provide them. You may optionally configure the
Meridian II to also set its hostname via DHCP, if your DHCP server is configured to provide it. You
can do this by running a simple script called netconfig after your unit is up on the network.
If your network does use DHCP for host configuration, and you are in a hurry to get your Meridian II
up and running, you may proceed to Verifying Network Configuration to make sure that the network
parameters were set up correctly. Otherwise, it is recommended that you read the following sections
on the use of the RS-232 serial I/O port now, since they will help you in debugging any problems thatyou may encounter with the automatic configuration via DHCP.
If your network does not use DHCP, you will need to configure your Ethernet interfaces using either
the front-panel keypad or the RS-232 serial I/O port. The following sections contain brief descriptions on how to do that.

Configuring Ethernet with the Front-Panel Keypad

Configuring your Ethernet interfaces with the front-panel keypad is quite simple. After the unit has
powered on, press the ENTER key once or twice until you see a display called Main Menu. Now
press the RIGHT arrow key until the “Network” selection is highlighted. Then highlight either “Network4” or “Network6” and press ENTER again. Now you can choose which port to set up - either
eth0 or eth1. You will then be able to start modifying the IP address, gateway and netmask by
10

Meridian II User ManualB A S I C I N S TA L L AT I O N

pressing the EDIT key. The sequence of displays will guide you through the setup process. Press the
HELP key at any time to view context-sensitive help information. When you are finished choose the
REBOOT menu item and initiate a system reboot.

Configuring Ethernet with the Serial Port

To configure your Ethernet interfaces with the serial port, after logging in as the root user, you mustrun a simple script called netconfig. This script will prompt you for the needed information andperform some syntax checking on your inputs. Then it will create or modify the appropriate files
needed to configure the Ethernet interface. The following sections will guide you in setting up communications with the Meridian II using its RS-232 serial I/O port.
Connect the RS-232 Serial I/O Port
To test serial communications with the Meridian II you will need either a VT100 compatible terminal
or a terminal emulation program running on your computer. We will refer to either of these as “terminal” for the remainder of this instruction.
1. Disconnect power from the Meridian II.
2. Connect one end of the DB9F-to-DB9F null modem adapter cable to the serial I/O jack on the
Meridian II.
3. Connect the other end of the DB9F-to-DB9F null modem adapter cable to the terminal. If theserial I/O port on your terminal does not have a DB9M connector, you may need to use an adapter.
Refer to Appendix K - Specifications for details on the signal wiring. If you are using a computerfor your terminal, remember which port you are using because you will need to know that in order to
set up your terminal software.

NOTE
You must use an RS-232 null-modem cable or adapter if you are connecting the Meridian II to anothercomputer. The cable included in the shipping kit is a null-modem cable.
If your computer does not have a serial port, you can use a USB port with a USB-RS232 converter similar
to Gearmo GM-FTDI-8. First, connect the USB converter to your computer, then connect the converter tothe null-modem cable. Finally, connect the null-modem cable to the Meridian II.
Test the Serial Port
You must configure your terminal to use the serial I/O port you used in Connect the RS-232 Serial
I/O Port above. You must also configure your terminal as shown below:
•
•
•
•
•
•
11

Baud Rate: 19200
Data Bits: 8
Parity: None
Stop Bits: 1
Handshaking / Flow Control: OFF (both hardware and software)
Terminal Emulation (if any): VT100 (or similar) or Linux
Meridian II User ManualCHAPTER TWO

After configuring these parameters in your terminal, apply power to the Meridian II. After about 20
seconds, your terminal should display something similar to this:************************************************************** 6010-0066-000 Linux Bootloader v1.00 Jan 1 2013 21:24:16 **************************************************************
Default kernel: FACTORY
To override and boot the UPGRADE version of the kernel, type UPGRADE within 5 seconds.....
Booting with FACTORY Kernel
Default Root File System: FACTORY
To override and boot the UPGRADE version of the Root File System, type UPGRADE within 5 seconds.....
Booting with the FACTORY Root File System

These lines are the Linux bootloader boot prompts. These prompts will timeout after five seconds
and the factory default Linux kernel and the factory default Meridian II root file system will be loaded. When the Linux kernel is loaded from FLASH memory into RAM a long list of kernel-generated,
informational messages is displayed as the kernel begins execution and the various device drivers are
initialized. When the boot process completes, the Meridian II login prompt is displayed:*********************************************************************************
Welcome to Meridian II GPS console on: Meridian_II.your.domain*
Tue Feb 20 2013 21:47:03 UTC********************************************************************************
Meridian II login:

Here you may log in as “sysuser” with password “Praecis” or you may log in as the “root” user withpassword “endrun_1”. When logged in as “sysuser”, you may check status information and view log
files but you will not be able to modify any system settings or view secure files. In order to performsystem setup procedures, which includes configuring the IP network settings, you must log in as the“root” user. After correctly entering the password at this prompt,
password:

the sign on message is shown. It identifies the host system as Meridian II and shows the softwarepart number, version and build date. The out-of-the-box hostname is set to “Meridian_II”, and thedomainname is set to “your.domain”.
Meridian II GPS 6010-0067-000 v 1.00 Sat Jan 19 14:17:44 UTC 2013
Meridian II GPS (root@Meridian II:~)->

This last line is the standard Meridian II prompt. After configuring the unit, you should change thepasswords using the Linux passwd command issued from the prompt.
If you do not see characters displayed by your terminal program within 30 seconds after the unit ispowered up, you must troubleshoot your setup. An incorrectly wired cable or incorrect port setting inyour terminal emulation program are the most common problems. Refer to Appendix K - Specifications for the signal connections for the Meridian II.
Once you have successfully established communications with the Meridian II, you may proceed toconfigure the network parameters using netconfig (see below). Then you can communicate with
12

Meridian II User ManualB A S I C I N S TA L L AT I O N

the Meridian II over the network using telnet or ssh and synchronize your network computers to
UTC using NTP.
Using netconfig to Set Up Your IP

NOTE
When setting up the IP addresses on both network port 0 (eth0) and 1 (eth1):
1. Be sure that they are NOT on the same subnet.
2. Configure the default gateway on either port 0 (eth0) or port 1 (eth1), but NOT both.

NOTE
If you want to use the HTTPS Interface, then be sure to configure the name server IP address during thenetconfig process. The HTTPS Interface will not operate properly if this is configured incorrectly. Only
one name server is required, but two gives some redundancy.
The following shows the beginning of the netconfig interactive script:********************************************************************************************** Meridian II GPS IPV4/IPV6 Network Configuration *************************************************************************************************
This script will configure the TCP/IPV4/IPV6 network parameters for your **Meridian II GPS. We will first configure IPV4 and then IPV6. Your**
Meridian II GPS has two Ethernet interfaces, called eth0 and eth1. For**
each of IPV4 and IPV6, we will first configure eth0 and then eth1.
****
You can choose to keep the existing configuration of either interface and **reconfigure the other. You can also choose to “unconfigure” either of**
the two interfaces if both are not needed in your application.
****
You will be able to reconfigure your system at any time by typing:****
netconfig****
The settings you make now will not take effect until you reboot your**Meridian II GPS, so if you make a mistake, just re-run this script before **rebooting.
****
You will be prompted to enter your IPV4/IPV6 network parameters now.
*****************************************************************************************************************************************************************
Configure IPV4 for either eth0 or eth1?
(Answer yes to continue on and reconfigure either eth0 or eth1 for IPV4.)(Answer no to “unconfigure” both eth0 and eth1 for IPV4. Only the
IPV4 loopback interface will be setup.) ([y]es, [n]o):13

Meridian II User ManualCHAPTER TWO

After configuring your Ethernet interfaces, you should shutdown the Meridian II and reboot it by issuing this command at the prompt:
Meridian II GPS(root@Meridian II:~)-> reboot

Verify Network Configuration

If you are using the RS-232 serial I/O port to communicate with the Meridian II, you will be able tosee the kernel-generated boot messages when the unit reboots. You should note the lines
Configuring eth0 as 192.168.1.120...
Configuring eth1 as 192.168.5.1...

if you have set up a static IP address, or these lines
Attempting to configure eth0 by contacting a DHCP server...
Attempting to configure eth1 by contacting a DHCP server...

if you are using DHCP. These appear near the end of the kernel generated boot messages.
If you are using DHCP and are not using the RS-232 serial I/O port, you will have to check the DHCP
configuration information maintained by your DHCP server to determine the expected IP address andlog in to the Meridian II using telnet or ssh to verify successful DHCP configuration. Refer to thesubsequent topics in this section Using Telnet and Using SSH, for details on logging in to the Meridian II that way. Once you have logged in, you may perform the following checks.
If you are not using DHCP, the IP address shown should match the static IP address which you
entered during the netconfig procedure. If so, log in as “root” at the login prompt and check theother configuration parameters using ifconfig:
Meridian II GPS(root@Meridian II:~)-> ifconfig
eth0

Link encap:Ethernet HWaddr 00:0e:fe:01:00:1c
inet addr:192.168.1.120 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:9694 errors:0 dropped:970 overruns:0 frame:0
TX packets:459 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:829805 (810.3 KiB) TX bytes:50242 (49.0 KiB)
Interrupt:11

eth1

Link encap:Ethernet HWaddr 00:0e:fe:01:00:1d
inet addr:192.168.5.1 Bcast:192.168.5.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:10143 errors:0 dropped:970 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:881081 (860.4 KiB) TX bytes:0 (0.0 B)
Interrupt:15

14

Meridian II User ManualB A S I C I N S TA L L AT I O NloLink encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:5808 errors:0 dropped:0 overruns:0 frame:0
TX packets:5808 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:728178 (711.1 KiB) TX bytes:728178 (711.1 KiB)

Pay particular attention to the settings shown for eth0 and eth1, in particular the Mask: setting,which should match that which is appropriate for your network. Now check the remaining configuration parameters using route:
Meridian II GPS(root@Meridian II:~)-> route
Kernel IP routing table
Destination
Gateway
Genmask
default
192.168.1.1
0.0.0.0
loopback*
255.0.0.0
localnet*
255.255.255.0
192.168.5.0*
255.255.255.0

Flags Metric Ref
UG
1
0
U
0
0
U
0
0
U
0
0

Use Iface0 eth00 lo
0 eth00 eth1

Here you are interested in the default gateway address. It should match the appropriate one for yournetwork. If so, then the Ethernet interface of your Meridian II has been successfully configured tooperate on your network and you are ready to check operation of the Meridian II over the network. If
not, you should recheck your configuration and/or repeat the netconfig procedure.
If you have configured a nameserver(s) for your network, you may check that by issuing this command:
Meridian II GPS(root@Meridian II:~)-> cat /etc/resolv.conf
search your.domainnameserver 192.168.1.1
nameserver 192.168.1.2

Which displays the contents of the /etc/resolv.conf file containing the domain name you entered previously using netconfig, and the nameserver IP address(es) to use for that domain.

Check Network Operation

With your Meridian II network parameters properly configured, you are ready to test the setup using
ping from a server or workstation that is able to access the network connected to the Meridian II.
Alternatively, you could ping one of your servers or workstations from the Meridian II prompt to test
the setup.
Once you have successfully established network communications with the Meridian II, you may perform all maintenance and monitoring activities via telnet and ftp. The Meridian II provides bothclient and server operation using telnet. For security reasons, only client operation is supported using ftp. You may also monitor the Meridian II via the HTTPS interface (see Chapter 7 - HTTPS).
Security conscious users will want to use ssh, the secure shell replacement for telnet, as the loginmeans. The companion utility, scp provides a secure replacement for ftp as a means of transferring
files to and from the Meridian II. Both of these protocols are supported in the Meridian II via the
OpenSSH implementations for Linux. Refer to Chapter 5 - Security, OpenSSH for more information
about the secure shell protocol.
15

Meridian II User ManualCHAPTER TWO

Using Telnet

When establishing a telnet connection with your Meridian II, logging in directly as root is not permitted. This is a security measure that makes it slightly more difficult to gain access by simply trying
passwords, since it is also necessary to know the name of a user. When you initiate a telnet session
with the Meridian II, this banner will be displayed:*********************************************************************************
Welcome to Meridian II GPS telnet console on: host.your.domain********************************************************************************
host login:

Here you may log in as “sysuser” with password “Praecis”. When logged in as “sysuser”, you may
check status information and view log files but you will not be able to modify any system settings orview secure files. After correctly entering the password at this prompt,
Password:

the sign on message is shown. It identifies the host system as Meridian II GPS and shows the software part number, version and build date:
Meridian II GPS 6010-0067-000 v 1.00 Sat Jan 19 14:17:44 UTC 2013
Meridian II GPS (root@Meridian II:~)->

This last line is the standard Meridian II prompt. After configuring the unit, you should change thepasswords using the Linux passwd command issued from the prompt.
To gain root access, you must now issue the “super user” command at the prompt:
Meridian II GPS(root@Meridian II:~)-> su root

You will then be prompted for the password, which is “endrun_1”, and be granted root access to thesystem. To leave “super user” mode, issue the command exit. Issuing exit again will close thetelnet session.

Using SSH

When establishing a ssh connection with your Meridian II, logging in directly as root is permitted.
When you log in as root via a ssh session with the Meridian II, this banner will be displayed:********************************************************************************
Welcome to the Meridian II GPS SSH console on: host.your.domain*******************************************************************************
root@M192.168.1.120’s password:

Here you may log in as “root” with password “endrun_1”. After correctly entering the password thesign on message is shown. It identifies the host system as Meridian II and shows the software partnumber, version and build date:
Meridian II GPS 6010-0067-000 v 1.00 Sat Jan 19 14:17:44 UTC 2013
Meridian II GPS (root@Meridian II:~)->

16

Meridian II User ManualB A S I C I N S TA L L AT I O NThis last line is the standard Meridian II prompt. After configuring the unit, you should change thepasswords using the Linux passwd command issued from the prompt.
Issuing exit will close the ssh session.

Using HTTPSYou may monitor the status of the Meridian II via the HTTPS interface. For security reasons, you
may not change any settings via the HTTPS interface. See Chapter 4 - HTTPS for more information.

IMPORTANT
SSH, Telnet, SNMP and HTTPS are all enabled with default passwords. To ensure security, change thepasswords or disable the protocols.
To change the passwords for SSH, Telnet and HTTPS use the Linux passwd command. To change thepasswords/community strings for SNMP see Chapter 6 - SNMP.
To disable Telnet, SSH, SNMP and HTTPS see Chapter 5 - Security, Disable Protocols.

Connecting Instruments
to the Meridian II

Rear-panel mounted BNC ports provide the means of connecting your equipment to the Meridian II.
The standard Meridian II provides two precision output signals capable of driving properly terminated coaxial cables: 1 PPS and AM Code. These two signals are DC-coupled and sourced from
Advanced CMOS (ACMOS) drivers which are able to maintain output TTL levels into a 50-ohm
load. The optional low-phase noise, spectrally pure sine wave outputs are capable of driving 1 Vrms
into a 50-ohm load. If your unit is equipped with other optional timing or frequency outputs, thesewill also be designed to drive a 50-ohm load. Care should be taken not to short circuit these outputs
or to connect them to other voltage sources.
If your unit is equipped with the optional Alarm Output, it will be available on a rear-panel BNC jacklabeled “ALARM”. Care should be taken not to directly connect this open-collector output to a voltage source. A series current-limiting resistor of at least 1k ohms in value should be used. The pull-up
voltage must not exceed 40V.
If your primary application for the Meridian II is as a frequency standard and you have not purchased
one of the optional higher-stability oscillators, you should consider operating with the display set toview the Receiver State. (See Chapter 13 - Front-Panel Keypad and Display.) With this display inview you will always know whether the Meridian II is currently locked to a GPS signal while you are
performing measurements based on its frequency outputs. The holdover frequency accuracy of thestandard TCXO will degrade to the 5x10-8 level fairly quickly following GPS signal loss, depending
upon the ambient temperature.

17

Meridian II User ManualCHAPTER TWO

Refer to Chapter 10 - Rear-Panel I/O and to Appendix K - Specifications for more information on
the rear-panel output signals.

18

Meridian II User Manual

"Smarter Timing Solutions"

Chapter Three

Console Port Control and Status
This chapter describes Meridian II control and status commands used via the Linux console. The
console is accessed via any of the Ethernet ports or the RS-232 serial port. Meridian II supports several application-specific commands for configuration and for monitoring the performance and statusof the Linux and GPS Subsystems.
You do not need knowledge of Linux commands in order to operate Meridian II. However, Meridian II does support a subset of the standard Linux commands and utilities and it uses the bash shell,
which is the Linux standard, full-featured shell. A wealth of information is available from a variety ofother sources on Linux.
Meridian II-specific commands will be described in this chapter. For a brief description of some of
the most useful Unix/Linux commands, see Appendix C - Helpful Linux Information.

Console Ports

General Linux
Operation

Three interface ports are available on Meridian II. Two are 10/100/1000Base-T Ethernet ports andone is an RS-232 serial port. Network cables and a serial cable are provided with each Meridian II
shipment. The serial cable is wired as a null-modem adapter and can be used to connect Meridian II
to the serial port on your computer. Detailed specifications on the ports, including the RS-232 pinout,
are in Appendix K - Specifications.

You do not need to know Linux in order to operate Meridian II. However, for those interested, thecommand shell used by Meridian II is the Linux standard: bash. All commands and file names arecase sensitive, which is standard for Unix-like operating systems. For a brief description of some of
the most useful Unix/Linux commands, see Appendix C - Helpful Linux Information.
If you are unfamiliar with Unix-like operating systems, and you would like to be able to more closely
monitor or optimize the performance of your Meridian II then you should consult good Linux reference books or the Linux Documentation Project at:
tldp.org

19

Meridian II User ManualCHAPTER THREE

Available User Commands
COMMAND
accessconfig

antfltmask
caldelayclearalmanac
cpuio
cpuioconfig
cpustatdumpalmanac
dumpephemeris
faultstatget_sw_opts
gpsdynmodegpsionoinfo
gpslastfix
gpsrefpos
gpsrefpos_ecef
gpsstat
gpstrkstat
gpsutcinfo

gpsversion

20

FUNCTION
Interactive script that guides you in configuring
telnet, ssh and snmpd access to Meridian II that is limited
to specific hosts. The resulting /etc/hosts.allow and/etc/hosts.deny files are saved to the non-volatile FLASH disk.
Factory default configuration allows access by all hosts.
Prints the current setting for the Antenna Fault Mask.
See the setantfltmask command.
Prints the calibration delay. See the setcaldelay command.
For use with a GPS simulator. See Appendix J - Operation
with a GPS Simulator.
Returns the current settings for CPU Module outputs such as
1 PPS and time code.
An interactive utility that allows you to modify the settings for
the CPU Module outputs.
Prints the current Linux CPU core temperature, system load as
percent of maximum and free memory available.
Prints the current GPS almanac data for all satellites in Yuma
format.
Prints the last received GPS ephemeris data for all satellites in
Rinex 3.01 format.
Prints the summary of all system fault states in a user-friendly
format.
Prints the software options enabled in your Meridian II. See
Appendix I - Software Options for more information.
Prints the GPS dynamic mode currently in effect.
See the setgpsdynmode command.
Prints the GPS Ionospheric Model Almanac parameters per the
IS-GPS-200.
Prints the last computed GPS position fix.
Prints the GPS reference position.
See the setgpsrefpos command.
Prints the GPS reference position in Earth-Centered EarthFixed format.
Prints the GPS Subsystem status information.
Prints the GPS satellite tracking status. Azimuth, elevation andsignal level (C/No) are shown for each satellite.
Prints the GPS UTC Almanac parameters per the IS-GPS-200.
Also shows the current calculated GPS-UTC offset, which
includes leap seconds and a small sub-second offset.
Prints the GPS Subsystem firmware and FPGA version information.

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help
help command
hp5071astat(optional)
inetdconfig

inhibitoutputsmodeinstalled_sw_opts
ionostat(optional)
kernelversion
kplockstat
lockoutkp
logrinex
netconfig
ntpconfig

ntpstatoscctrlstat
passwdpluginopts

pluginoptsconfig

21

Prints help for all Meridian II-specific (not Linux) commands.
Prints command-specific help. For example: help gpsstat.
For use with the 5071A Cesium Control Module. See Chapter
10 - Rear Panel I/O, 5071A Control Module.
Interactive script that allows you to configure the list of protocol servers which are started by the inetd server daemon
running in Meridian II.
Prints the current InhibitOutputsMode setting which controls
the timing output signals (time codes and pulse rates) prior toinitial lock to GPS.
See the setinhibitoutputsmode command.
Prints the software options enabled in your Meridian II. See
Appendix I - Software Options for more information.
Prints the status of the optional RTIC. See Chapter 11 - RealTime Ionospheric Corrections for more information.
Prints the Linux operating system kernel version.
Prints the front-panel keypad lockout status.
See the lockoutkp and unlockkp commands.
Command to lock out access to the front-panel keypad EDIT
key. See the kplockstat and unlockkp commands.
Controls logging of raw GPS pseudorange and carrier phaseobservations in Rinex 2.11 format.
Interactive script that allows you to configure the IP network
subsystem of Meridian II.
Interactive script that guides you in configuring the NTP
Subsystem. Allows configuration of MD5 authentication andbroadcast/multicast mode. All parameters are retained in nonvolatile FLASH disk storage.
Prints the values of several key parameters indicating the statusof the NTP daemon. These include the current offset between
the NTP-steered system clock and the GPS Subsystem clock,and the current counts of received packets, sent packets anddropped packets. In addition the current sent packet rate isshown.
Prints the system oscillator disciplining parameters.
Used to change the password for the user that you are logged
in as.
Returns the board type and settings for any installed plug-in
option boards. See Chapter 10 - Rear-Panel I/O, Plug-In
Module Options for more information.
An interactive script that allows the user to change the settingson any configurable plug-in option board. See Chapter 10- Rear-Panel I/O, Plug-In Module Options for more information.

Meridian II User ManualCHAPTER THREE

ptpconfig0
ptpconfig1(optional)
ptpstat0
ptpstat1(optional)
pwrfltmask(optional)
rcvrserialnumber
rcvrstatrcvrversion
resetlastgpswn
resetleaphistory
rticmode(optional)
serialnumber
setantfltmask
setcaldelay
setgpsdynmode
setgpsrefpos

setinhibitoutputsmodesetpwrfltmask(optional)
setrticmode(optional)
setsigfltmask
settfomfltlvl
sigfltmask

22Interactive script that guides you in configuring parameters forthe optional PTP/IEEE-1588 protocol. See Chapter 9 - PTP/
IEEE-1588 for more information.
Prints the status of the optional PTP/IEEE-1588 Subsystem.
See Chapter 9 - PTP/IEEE-1588 for more information.
Prints the current settings of the optional Dual Power Supply
Input Fault Alarm Masks. See Chapter 10 - Rear-Panel I/O,
Power Supply Options for more information.
Prints the serial number of the GPS Receiver.
Prints the status of the GPS Receiver.
Prints the GPS Receiver firmware and FPGA version information.
For use with a GPS simulator. See Appendix J - Operation
with a GPS Simulator.
For use with a GPS simulator. See Appendix J - Operation
with a GPS Simulator.
Prints the mode of the RTIC Option - either ON or OFF. See
Chapter 11 - Real-Time Ionospheric Corrections for more
information.
Prints the serial number of the Meridian II.
Command to enable or mask the Antenna Fault.
See the antfltmask command.
An interactive utility that allows you to change the clock calibration delay. See the caldelay command.
Command to set the dynamic mode of operation of the GPS
Subsystem. See the gpsdynmode command.
Interactive utility that prompts you for an accurate reference
position, performs syntax and argument validity checking thenpasses the position to the GPS Subsystem.
See the gpsrefpos command.
Sets the InhibitOutputsMode setting which controls the timing
output signals (time codes and pulse rates) prior to initial lockto GPS.
See the inhibitoutputsmode command.
Command to enable or mask the optional Dual Power Supply
Input Faults. See Chapter 10 - Rear-Panel I/O, Power Supply
Options for more information.
Sets the RTIC mode - either ON or OFF. See Chapter 11 Real-Time Ionospheric Corrections for more information.
Command to enable or mask the Signal Loss Fault.
See the sigfltmask command.
Command to change the TFOM fault level
Prints the current setting for the Signal Loss Fault mask.
See the setsigfltmask command.

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subsysresetsyskernel

upgradekernel

Command that performs a GPS Subsystem reset.
Prints the currently booted linux kernel, either 0 or 1, where 0
is the factory-installed kernel and 1 is the upgraded kernel.
Prints the installed system oscillator type, which is one of
TCXO, MS-OCXO, HS-OCXO, US-OCXO, Rubidium or USRubidium.
Prints the currently loaded linux root file system image, either
0 or 1, where 0 is the factory-installed root file system, and 1 isthe upgraded root file system.
Prints detailed NTP status information. Included is the offsetof the NTP-steered system clock to the GPS Subsystem clock,the NTP daemon leap indicator bit values, the TFOM, the timeof the most recent update and the current leap seconds value.
Returns the current settings for installed system outputs such as
1 PPS and time code.
An interactive utility that allows you to modify the settings forthe system options.
Prints the time mode settings in effect for the front-panel display, the Time Code Output, or the optional Serial Time output.
See the systimemodeconfig command.
Interactive utility that guides you in configuring the time modesettings for the front-panel display, the Time Code Output, or
the optional Serial Time Output. Allows setting to the LOCAL,
GPS or UTC timescale. See the systimemode command.
Prints the Linux root file system version information.
Prints the current setting for the TFOM Fault Level.
Starts execution of the Trigger PPO function. See Chapter 10- Rear-Panel I/O, Programmable Pulse Output (PPO) Option
for more information.
Command to unlock access to the front-panel keypad EDIT
key. See the lockoutkp and kplockstat commands.
Command to update the flag stored in FLASH that is read by
the Linux bootloader at boot time to select operation with either
the factory-installed or upgraded kernel.
Command to update the flag stored in FLASH that is read by
the Linux bootloader at boot time to select operation with either
the factory-installed or upgraded root file system.
Command that performs the Linux Kernel upgrade process.

upgradercvr

Command that performs the GPS Receiver upgrade process.

upgradercvrfpga

Command that upgrades the FPGA resident on the GPS Receiver.
Command that performs the Linux Root File System upgrade
process.
Command that performs the GPS Subsystem firmware upgrade
process.

sysosctype

sysrootfs

sysstatsystemiosystemioconfig
systimemodesystimemodeconfig

sysversion
tfomfltlvl
triggerppo(optional)
unlockkp
updatekernelflag

updaterootflag

upgraderootfs
upgradesubsys

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wrt_sw_opt

Detailed Command
Descriptions

Command to enable a software option. See Appendix I - Software Options for information.

accessconfig

This command starts an interactive script that will allow the root user to configure access limitation
via telnet, ssh and snmp to Meridian II. By default, the unit is configured to allow access by allusers. If you need to limit telnet, ssh or snmp access, e.g. for security reasons, you must run thisscript as root from either the RS-232 serial I/O port or from a telnet or ssh session.
This script modifies these files: /etc/hosts.allow and /etc/hosts.deny. These are non-volatilely stored
in the FLASH disk /boot/etc directory. You must reboot Meridian II after running this script for thechanges to take effect.
Command:accessconfig
Meridian II reply:Interactive script is started.

antfltmask

This command displays the current setting for the Antenna Fault Mask.
Command:antfltmask
MeridianII reply: Antenna Fault is ENABLED

caldelay

This command displays the current calibration delay setting for the GPS antenna cable. The allowable calibration delay range is ±500,000 nanoseconds. See Appendix E - Installing the GPS
Antenna, Calibrate Your Receiver for more details.
Command:caldelay
MeridianII reply: +0 nanoseconds

clearalmanac

This command is for use with a GPS simulator Refer to Appendix J - Operation with a GPS Simulator for more information.

cpuioThis command displays the current settings for the CPU Module outputs. See Chapter 10 - RearPanel I/O, Standard I/O and CPU Module Options for more information. Below is an example
response showing the standard outputs on A and B, with an optional output on C.

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Command:cpuio
MeridianII reply: CPU I/O A - AM TIME CODE OUTPUT is Installed -Current Setting = (See systemio command)
CPU I/O B - 1 PPS OUTPUT is Installed -Current Setting = (See systemio command)
CPU I/O C - PROGRAMMABLE PULSE OUTPUT is Installed -Current Setting = 1M PPS

cpuioconfig

This command starts an interactive shell script that will allow the root user to change the settings ofany installed, user-selectable, CPU Module outputs. Usually, this would be the Programmable Pulse
Output (PPO). See Chapter 10 - Rear-Panel I/O, Standard I/O and CPU Module Options for more
information.
Command:cpuioconfig
MeridianII reply: Interactive shell script is started.

cpustatThis command shows a group of key values for monitoring the health of the Linux CPU and operating system status. The format is:YYYYMMDD.HH:MM:SS LLL% FREEkB +TT.TC

Where:YYYY

is the year of the UTC timestamp of the most recent update.

MMDD

is the month and day-of-month of the UTC timestamp of the most recent update.

HH:MM:SS is the hour, minute and second of the UTC timestamp of the most recent update.
LLL%

is the percentage of maximum load as returned using the Linux vmstat command.

FREEkBis the available free memory in kilobytes as returned using the Linux vmstat command.

+TT.TCis the temperature in degrees centigrade of the Linux CPU die temperature.

Command:cpustatMeridianII reply: 20130116.22:24:00

23% 320056kB+67.9C

dumpalmanac

This command prints the current GPS almanac data for all satellites in Yuma format.
Command:
dumpalmanac
MeridianII reply: Example shown below, for satellite 01

25

Meridian II User ManualCHAPTER THREE****** Week 1890 almanac for PRN-01 *******
ID:
01
Health:000
Eccentricity:
5.217074882e-03
Time of Applicability(s):5.038080000e+05
Orbital Inclination(rad):9.637917876e-01
Rate of Right Ascen(r/s): -7.828898418e-09
SQRT(A) (m 1/2):
5.153603027e+03
Right Ascen at Week(rad): -1.158766985e+00
Argument of Perigee(rad): +4.515030086e-01
Mean Anom(rad):-2.085680962e+00
Af0(s):+1.621245974e-05
Af1(s/s):+0.000000000e+00
week:
1.890000000e+03

dumpephemeris

This command prints the current GPS ephemeris data for all satellites in Rinex 3.01 format.
Command:dumpephemeris
MeridianII reply: Example shown below, for satellite 01
G01 2016 03 30 20 00 00 +1.58743932843e-05 +1.13686837722e-12 +0.00000000000e+00+8.00000000000e+01 -1.13437500000e+01 +4.30446501253e-09 -2.12893752067e+00-5.90458512306e-07 +5.20769448485e-03 +8.78982245922e-06 +5.15364822960e+03+3.31200000000e+05 -1.26659870148e-07 -1.15738910133e+00 -5.58793544769e-09+9.63788168503e-01 +2.12843750000e+02 +4.50864037440e-01 -7.82032574796e-09+3.27513642258e-10 +1.00000000000e+00 +1.89000000000e+03 +0.00000000000e+00+2.00000000000e+00 +0.00000000000e+00 +5.12227416039e-09 +8.00000000000e+01+3.24258000000e+05 +4.00000000000e+00 +0.00000000000e+00 +0.00000000000e+00

faultstat

This command returns the summary of all system and receiver fault states in a user-friendly format.
An example is shown below. For details on the various faults see Appendix G - System Faults.
Command:faultstat
MeridianII reply: System Fault Status:
System Oscillator DAC--------------------------> OK
GPS Signal-------------------------------------> OK
GPS Subsystem FPGA Configuration---------------> OK
GPS Subsytem FLASH Writes----------------------> OK
GPS Receiver Communication---------------------> OK
GPS Reference Time-----------------------------> OK
Subsystem Communication------------------------> OK
GPS Receiver-----------------------------------> *FAULT*System Oscillator PLL--------------------------> OK
GPS Antenna------------------------------------> *FAULT*
Plug-In Options--------------------------------> OK
System Power/Configuration---------------------> OK
GPS Receiver Fault Status:
GPS Receiver Oscillator DAC--------------------> OK
GPS Signal-------------------------------------> OK
GPS Receiver FPGA Configuration----------------> OK
GPS Receiver FLASH Writes----------------------> OK

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Local Oscillator Synthesizer Tuning------------> OK
Local Oscillator Synthesizer-------------------> OK
GPS Reference Time-----------------------------> OK
GPS Receiver Oscillator------------------------> OK
GPS Antenna Short------------------------------> OK
GPS Antenna Open-------------------------------> *FAULT*GPS Receiver Oscillator PLL--------------------> OK

get_sw_opts

See Appendix I - Software Options for information on this command.

gpsdynmode

This command displays the current GPS Subsystem dynamic mode of operation. It has two possible
settings: OFF or ON. When it is OFF, it is assumed that Meridian II is installed in a stationary location. When it is ON, it is assumed that Meridian II is installed on a moving platform. Dynamic mode
is intended for shipboard applications only.
When the dynamic mode is OFF, Meridian II will use its accurate reference position to implement
Timing Receiver Autonomous Integrity Monitoring (TRAIM) for the utmost in reliability during any
GPS system faults. In addition, single satellite operation is possible once an initial accurate position
has been determined.
When the dynamic mode is ON, only a very minimal TRAIM algorithm is in effect because the accurate reference position is not static. In addition, a minimum of four satellites must be visible andonly 3-D position fixes are used. When the dynamic mode is ON, the source reported for the accurate
reference position by gpsrefpos is set to DYN. Dynamic mode is intended for shipboard applications only.
Command:gpsdynmode
MeridianII reply: OFFgpsionoinfo

This command provides the current and previously received GPS ionospheric model coefficients.
Also shown are the week number and time-of-week of the almanac transmissions that contained thetwo sets of model coefficients.
Command:gpsionoinfo
MeridianII reply:

GPS Ionosphere Model Almanac Parameters:
WN_a = 1890 T_oa = 503808
Alpha0 = +1.676e-08 Alpha1 = +7.451e-09
Beta0 = +1.106e+05 Beta1 = +1.638e+04
WN_a = 1890 T_oa = 405504
Alpha0 = +1.676e-08 Alpha1 = +7.451e-09
Beta0 = +1.106e+05 Beta1 = +1.638e+0427

Alpha2 = -1.192e-07
Beta2 = -2.621e+05

Alpha3 = -5.960e-08
Beta3 = -6.554e+04

Alpha2 = -1.192e-07
Beta2 = -2.621e+05

Alpha3 = -5.960e-08
Beta3 = -6.554e+04

Meridian II User ManualCHAPTER THREE

gpslastfix

This command provides the last computed GPS position. When tracking four or more satellites, theGPS Receiver may provide a 3D-position fix, otherwise an overdetermined time-only solution will becomputed. The last-fix position is unaveraged and typically less accurate than the reference position, but it does provide a good indication that the receiver is working properly. Position is provided
in latitude, longitude and height above the WGS-84 ellipsoid. PDOP, HDOP, VDOP and TDOP are
also shown. OORCnt is the out-of-range counter which may be non-zero when Meridian II has been
moved more than 1 km from its previous location without being placed in UNKNOWN mode using
the setgpsrefpos command. It could also be non-zero during a GPS system anomaly, in whichcase Meridian II TRAIM algorithms will be operating to maintain the integrity of the system timing.
Command:gpslastfix
MeridianII reply: LAST POSITION FIX = N38d24m54.33s W122d45m10.99s +00003.5 meters
PDOP:

2.90 HDOP:

1.48 VDOP:

2.49 TDOP:

2.03 OORCnt:0

gpsrefpos

This command displays the current GPS Subsystem reference position. The source of the position,
which is one of UNK (unknown), DYN (dynamic), USR (user entered) or AVG (24 hour average ofGPS fixes) is displayed first. The WGS-84 latitude and longitude in degrees, minutes, seconds format
and the height above the WGS-84 reference ellipsoid in meters follow. Also, the current RMS PDOPof the average position and the current count of averages are shown. If the reference position source
is not AVG, then these two values will be zero.
Command:gpsrefpos
MeridianII reply:

CURRENT REFERENCE POSITION = AVG N38d24m54.30s W122d45m10.95s +00004.1 meters
RMSPDOP: 2.4 AvgCnt: 28800

gpsrefpos_ecef

This command displays the current GPS Subsystem reference position in Earth-Centered Earth-Fixed
format. The source of the position, which is one of UNK (unknown), DYN (dynamic), USR (userentered) or AVG (24 hour average of GPS fixes) is displayed first. The WGS-84 X, Y, Z coordinates
in meters are displayed next. Then, the current RMS PDOP of the average position and the current
count of averages are shown. If the reference position source is not AVG, then these two values will
be zero.
Command:gpsrefpos_ecef
MeridianII reply:

CURRENT REFERENCE POSITION ECEF = AVG X: -2707225.0 m Y: -4208361.2 m Z: +3941650.2 m
RMSPDOP: 2.4 AvgCnt: 28800

gpsstatThis command allows you to query the status of the GPS Subsystem. During normal operation,
the system polls the GPS Subsystem every 10 seconds. The results of this poll are used to steer thesystem clock and are saved to a log file. This command parses and formats the data contained therein
and prints this fixed-length string having these fields:

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LKSTAT TFOM = ? YEAR DOY HH:MM:SS LS LF S NN AGC EFCDAC C/No FLTR FLTS

Where:LKSTATis the tracking status of the GPS Subsystem, either LOCKED or NOTLKD.

TFOM = ? is a value between 3 and 9 and indicates clock accuracy.
A detailed explanation of TFOM is in Appendix A - TFOM.
YEAR

is the year of the UTC timestamp of the most recent update.

DOY

is the day-of-year of the UTC timestamp of the most recent update.

HH:MM:SS is the hour, minute and second of the UTC timestamp of the most recent update.
LS

is the current number of leap seconds difference between the UTC and GPS timescales(18 at the time of this writing).

LF

is the future (at the next UTC midnight) number of leap seconds difference between the
UTC and GPS timescales (18 at the time of this writing).

S

is the Signal Processor State, one of 0 (Acquiring), 1 (GPS Locking), 2 (GPS Locked), 9(Warming Up).

NN

is the number of GPS satellites being tracked, 0 to 12.

AGC

is the RF front-end Automatic Gain Control 8-bit DAC value. Typical range is 125 to200, with larger numbers implying higher gain being used.

EFCDAC is the system oscillator Electronic Frequency Control 20-bit DAC value, 0 to 1048575
with larger numbers implying higher oscillator frequency. Typical range is 320000 to
680000.
C/No

is the received GPS Carrier Signal-to-Noise Ratio, 0.00 to 99.9, measured in dB in a 1Hz
bandwidth. Typical range is 39 to 50.

FLTR

is the fault status for the GPS Receiver. This is a numeric value consisting offour hexadecimal characters where each bit indicates a particular receiver fault.
Assertion of any of these bits will light the Alarm LED. Bit definitions are shown below,
Decoding the bits can be difficult for non-programmers. For a more user-friendly methodof reading the fault status use the faultstat command. For details on each systemfault see Appendix G - System Faults.

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Char 0Char 1
Char 2Char 3FLTS

Bit 3
GPS Rcvr
FLASH Writes
GPS Rcvr
Oscillator
N/A
N/A

Bit 2
GPS Rcvr
FPGA Config
GPS ReferenceTime
Rcvr Osc PLL
N/A

Bit 1
GPS Signal
Synthesizer

Bit 0
GPS Rcvr
Oscillator DAC
Synthesizer Limits

Antenna Open
N/A

Antenna Short
N/A

is the fault status for the GPS Subsystem. This is a numeric value consistingof four hexadecimal characters where each bit indicates a particular system fault.
Assertion of any of these bits will light the Alarm LED. Bit definitions are shown below.
Decoding the bits can be difficult for non-programmers. For a more user-friendly methodof reading the fault status use the faultstat command. For details on each systemfault see Appendix G - System Faults.

Char 0

Bit 3
FLASH Writes

Char 1

GPS ReceiverChar 2

GPS AntennaChar 3

System Power/
Configuration

Bit 2
FPGA
Configuration
Subsystem
Communication
System Osc PLL
N/A

Bit 1
GPS Signal
GPS Reference
Time
Secondary Power
Supply5071A

Bit 0
System Oscillator
DAC
GPS ReceiverCommunication
Primary Power
SupplyPlug-in Option

The Primary and Secondary Power Supply bits are only used if your Meridian II has the Dual-Redundant Power Supply option. The 5071A bit is used only if the 5071A Cesium Control Module isinstalled.
The example reply below indicates that there has been a period without tracking a GPS signal thatexceeded the time-out period, that there was a FLASH Write Fault and that there is an Antenna Fault.
Command:
gpsstatMeridianII reply:
LOCKED TFOM = 4 2001 092 04:48:56 13 13 2

7 151 328605 41.6 0200 0880

gpstrkstat

This command displays the current GPS Subsystem satellite tracking status. A list of twelve satellite
numbers along with azimuth, elevation and C/No is displayed for each receiver channel. Satellite
number 0 is an invalid number and indicates that no satellite is being tracked on that channel. Validsatellite numbers range from 1 to 32. Azimuth and elevation are in degrees and C/No is in dB.

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Command:
gpstrkstat
MeridianII reply: Ch SV Azimuth

Elev C/No
1 23 -108.41 +15.70 41.7
2 11 -118.21 +45.58 46.9
3 22 +107.41 +21.04 37.9
4 14 +52.10 +29.76 40.4
5 32 -40.36 +58.18 45.2
6 1 -79.14 +55.53 46.6
7 31 +127.87 +62.60 47.3
8 0
+0.00 +0.00 0.0
9 0+0.00 +0.00 0.0
10 0+0.00 +0.00 0.0
11 0+0.00 +0.00 0.0
12 0+0.00 +0.00 0.0

gpsutcinfo

This command displays the IS-GPS-200 almanac parameters which are used to relate GPS time toUTC. The first line of output contains the current (LS) and future (LSF) leap second values and the
GPS week number (WN_lsf) and day of week (DN) at the end of which the future leap second willtake effect. This could be in the past if a leap second insertion has recently taken place. Leap second
events occur every few years on either June 30 or December 31.
The second line of output contains the parameters for calculating the small residual offset between
the GPS master clock ensemble and UTC(USNO). This is typically less than 10 nanoseconds. The
remaining output shows the current value of the GPS-UTC offset.
Command:
gpsutcinfo
MeridianII reply: GPS UTC Almanac Parameters:

LS = 18 LSF = 18 WN_lsf = 1694 DN = 7
a0 = +9.313226e-10 a1 = -1.243450e-14 WN_t = 1727 t_ot =Current (GPS - UTC) Offset:
GPS - UTC = (18 + 3.810e-09) s @ WN = 1726, TOW = 434757

61440

gpsversion

This command displays the firmware and hardware versions of the GPS Subsystem.
Command:gpsversion
MeridianII reply:
F/W 6010-0076-000 Ver 1.00 - FPGA 6020-0016-000 Ver 01 - JUL 15 17:03:27 2015

help

This command displays a list of Meridian II commands (not Linux commands). To get help on aparticular command you would type help, followed by the command.
Command:help
MeridianII reply: Meridian II commands are displayed.
Command:help gpsstat
MeridianII reply: Information specific to the gpsstat command is displayed.
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hp5071astat

This command show the status of the optional 5071A Control Module.. Refer to Chapter 10 - RearPanel I/O, 5071A Cesium Control Module, Status Using the Console Port for more information.
Command:
hp5071astat
MeridianII reply: HP5071A is Not Installed

inetdconfig

This command starts an interactive script that allows you to configure the list of protocol servers
which are started by the inetd super-server daemon running in Meridian II. Three protocol servers
may be configured: Time, Daytime, and Telnet. By default, the unit is configured to start all of these
protocol servers. If you need to disable start-up of some or all of these, e.g. for security reasons, youmust run this script as root from either the RS-232 serial I/O port or from a telnet or ssh session.
This script modifies the /etc/inetd.conf file, which is non-volatilely stored in the FLASH disk /boot/etc directory. You must reboot Meridian II after running this script for the changes to take effect.
Command:inetdconfig
MeridianII reply: Interactive script is started.

inhibitoutputsmodeThis command shows the current inhibit mode of the timing signal outputs prior to initial system lockto the GPS receiver. If it is set to ON, then all timing signals will be inhibited (not present) until thesystem is locked to the timing receiver. If it is set to OFF, then the timing signals will be present on
the rear panel at all times.
Command:inhibitoutputsmode
MeridianII reply: OFF

installed_sw_opts

See Appendix I - Software Options for information on this command.

ionostat (Optional)

This command is only available if the RTIC option has been installed. Refer to Chapter 11 - RealTime Ionospheric Corrections for more information.

kernelversion

This command prints the current Linux operating system kernel firmware version.
Command:kernelversion
MeridianII reply:
6010-0064-000_v1.00 Linux Kernel 3.2.2-Sonoma #2 Dec 19 01:08:43 201232

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kplockstat

This command prints the status, either locked or unlocked, of the front-panel keypad EDIT key.
When the EDIT key is locked, it will prevent unauthorized tampering with the unit. All other keys
are still enabled so you may continue to read the status and current settings of Meridian II. Refer tothe lockoutkp and unlockkp commands.
Command:kplockstat
MeridianII reply: Keypad is UNLOCKED

lockoutkp

This command locks out access to the front-panel keypad EDIT key. When the EDIT key is locked,
it will prevent unauthorized tampering with the unit. All other keys are still enabled so you may
continue to read the status and current settings of Meridian II. Refer also to the kplockstat andunlockkp commands.
Command:lockoutkp
MeridianII reply: Keypad is LOCKED

logrinex

This command is used to control logging of raw GPS pseudorange and carrier phase observations in
the Rinex version 2.11 format to the /home/rinex/rinex.log file. It requires one argument, which may
be either ON or OFF.
If ON is asserted and logging is not currently in progress, then a new log of 2880 observations taken
every 30 seconds will begin. Assuming full constellation visibility, this will take 24 hours to complete. If a previously-initiated log is in progress, then an ON assertion will be ignored.
IMPORTANT!!! The data is always appended to the /home/rinex/rinex.log file, so if
you are performing multiple logs, it is up to you to manage the file and remove it
before it grows too large and fills the limited storage available.
If OFF is asserted, then any currently active log will be terminated. Data logged prior to the OFF
assertion is not discarded.
Once a complete log is available, you will need to prepend the Rinex version 2.11 header to it. An
example header is contained in a file in the same directory with the log file for reference:/home/rinex/rinex_header_2.11
You will need to edit various fields in it for your requirements. When you have a complete log withheader, you may submit it to the Natural Resources Canada website for Precise Point Position (PPP)
processing using the CSRS-PPP tool. This is the only freely-accessible PPP tool that will perform
single-frequency PPP processing that we are aware of. The web URL is :nrcan.gc.ca/maps-tools-and-publications/tools/geodetic-reference-systems/data/10923#

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Command:logrinex ON
MeridianII reply: Rinex Log Control Command Successful

netconfig

This command starts an interactive script that allows you to configure the IP network subsystem of
Meridian II. By default, the unit is configured to configure itself using the Dynamic Host Configuration Protocol (DHCP). If you need to set up static IP configuration, you must run this script as root
from the RS-232 serial I/O port during the installation process. Refer to Chapter 2 - Basic Installation, Using netconfig to Set Up Your IP for details on the use of the command.
This script creates or modifies these files: /etc/HOSTNAME, /etc/hosts, /etc/networks, /etc/resolv.conf
and /etc/rc.d/rc.inet1.conf. All of these are non-volatilely stored in the FLASH disk /boot/etc directory. You must reboot Meridian II after running this script for the changes to take effect.
Command:netconfig
MeridianII reply: Interactive script is started.

ntpconfig

This command starts an interactive script that allows you to configure the NTP Subsystem of Meridian II. By default, the unit is configured to authenticate its replies to clients using its default MD5
keys in the /etc/ntp.keys file. If you need to create your own MD5 keys (recommended) or set up
broadcast/multicast operation, you must run this script as root. Refer to Chapter 7 - Configuring the
NTP Server for details on the use of this command.
The two files that are modified are /etc/ntp.keys and /etc/ntp.conf. Both of these are non-volatilely
stored in the FLASH disk /boot/etc directory. You must reboot Meridian II after running this script
for the changes to take effect.
Command:ntpconfig
MeridianII reply: Interactive script is started.

ntpstatThis command provides some key information regarding the operation of the NTP daemon. It shows
the current offset between the NTP-steered system clock and the GPS Subsystem, the counts of received, sent and dropped packets, and the sent packet rate. The format of the response is:YYYYMMDD.HH:MM:SS +S.sssssssss RCVDCNT SENTCNT SENT/sec DROPCNT

Where:YYYY

is the year of the UTC timestamp of the most recent update received from the GPS Sub
system.

MMDD

is the month and day-of-month of the UTC timestamp of the most recent update received
from the GPS Subsystem.

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HH:MM:SS is the hour, minute and second of the UTC timestamp of the most recent update received
from the GPS Subsystem.
+S.sssssssss is the offset in seconds between the NTP system clock and the GPS Subsystem clock.
Positive implies that the system clock is ahead of the GPS Subsystem clock.
RCVDCNT is a count of the number of NTP packets received since startup of the NTP daemon.
This is a 32-bit counter so it will wrap back to zero after 4,294,967,295 packets.
SENTCNT is a count of the number of NTP packets sent since startup of the NTP daemon.
This is a 32-bit counter so it will wrap back to zero after 4,294,967,295 packets.
SENT/sec is the current rate of NTP packets being sent per second.
DROPCNT is a count of the number of NTP packets dropped since startup of the NTP daemon.
This is a 32-bit counter so it will wrap back to zero after 4,294,967,295 packets.
Below is an example of a typical response to this command:
Command:ntpstatMeridianII reply:
20130117.00:02:40 -0.000000051 129127988 129015079

1594.4/sec

15

oscctrlstat

This command displays the current values of the system oscillator control parameters. These parameters are related to the disciplined system oscillator. The command formats the data and prints this
fixed-length string having these fields:
YYYYMMDD.HH:MM:SS LKSTAT COAST ESTERR MEASERR TIMEDEV AGERATE TAU EFCDAC TEMP

Where:YYYY

is the year of the UTC timestamp of the most recent update received from the
GPS Subsystem.

MMDD

is the month and day-of-month of the UTC timestamp of the most recent update
received from the GPS Subsystem.

HH:MM:SSis the hour, minute and second of the UTC timestamp of the most recent update
received from the GPS Subsystem.

LKSTATis the GPS Subsystem control status, either WRM (warming up),
ACQ (acquiring), LKG (locking) or LKD (locked).

COAST

is the number of seconds the GPS Subsystem has been in coast mode
(unlocked to GPS).

ESTERR

is the estimated time error of the GPS Subsystem when in coast mode, inseconds.

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MEASERR

is the last measured time offset of the GPS Subsystem to GPS while locked, inseconds.

TIMEDEVis the time deviation (TDEV) of the offset measurements in seconds. The tau
associated with this measurement is three seconds, which is the update intervalof the position fixes received from the GPS Receiver.

AGERATEis the regression-computed system oscillator ageing rate per day (several-hour
delay before the first measurements are displayed).

TAU

is the system oscillator control loop averaging time constant, in seconds. It’svalue is automatically adjusted to maintain optimum offset and stability.

EFCDACis the system oscillator Electronic Frequency Control 20-bit DAC value. The
system automatically sets this value to remove frequency errors. Values may
range from 0 to 1048575. Values close to the maximum or minimum will set the
DAC fault flag that will appear in the fault status display. The Time/Status
display will also indicate a fault condition.

TEMP

is the chassis internal temperature in °C.

Below is an example of a typical response to this command:
Command:oscctrlstat
MeridianII reply:

20130117.00:23:10 LKD+50.750

0 6.26e-09 -6.26000e-09 1.25e-09 -6.93e-13 1955.3 524281

passwdThis command is used to change the password for the user that you are logged in as. It affects theserial port, SSH, Telnet and HTTPS. passwd is a Linux command that is also described in Appendix
C - Helpful Linux Information.
Command:passwdMeridianII reply: Interactive script is started.

pluginopts

This command displays the current settings for the installed plug-in option boards. See Chapter 10- Rear-Panel I/O, Plug-In Module Options for more information.
Command:pluginopts
MeridianII reply: Digital Buffer, 2001-0004-012-NC is installed-Serial Number 15070001
Port A Current Setting = 10M PPS.
Port B Current Setting = 5M PPS.
Port C Current Setting = 10 PPS.
Port D Current Setting = 10 PPS.

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pluginoptsconfig

This command starts an interactive shell script that will allow the root user to change the settings ofany installed, user-selectable, plug-in option board outputs. The user-selectable outputs are all boardspecific. For more information see Chapter 10 - Rear-Panel I/O, Plug-In Module Options.
Command:pluginoptsconfig
MeridianII reply: Interactive shell script is started.

ptpconfig0 and ptpconfig1 (Optional)

These commands are only available if the Precision Time Protocol (PTP) option has been installed.
Refer to Chapter 9 - PTP/IEEE-1588 for more information.

ptpstat0 and ptpstat1 (Optional)

These commands are only available if the Precision Time Protocol (PTP) option has been installed.
Refer to Chapter 9 - PTP/IEEE-1588 for more information.

pwrfltmask (Optional)

See Chapter 10 - Rear-Panel I/O, Masking Dual Power Supply Fault Alarms for information on
this command.

rcvrserialnumberThis command shows the serial number of the GPS Receiver in the Meridian II.
Command:rcvrserialnumber
MeridianII reply: 15080056

rcvrstat

This command shows three critical status parameters of the GPS Receiver: the number of satellites
currently being tracked, the automatic gain control DAC value for the receiver front end, and theaverage Carrier-to-Noise ratio of the tracked satellites.
Command:rcvrstat
MeridianII reply: 20150622.23:35:50 8 125 45.0

rcvrversion

This command displays the firmware and hardware versions of the GPS Receiver.
Command:rcvrversion
MeridianII reply:
F/W 6010-0081-000 Ver 1.00 - FPGA 6020-0014-000 Ver 01 - MAR 24 15:05:36 201537

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resetlastgpswn

This command is for use with a GPS simulator Refer to Appendix J - Operation with a GPS Simulator for more information.

resetleaphistory

This command is for use with a GPS simulator Refer to Appendix J - Operation with a GPS Simulator for more information.

rticmode (Optional)

This command is only available if the RTIC option has been installed. Refer to Chapter 11 - RealTime Ionospheric Corrections for more information.

serialnumberThis command shows the serial number of the Meridian II.
Command:serialnumber
MeridianII reply: 15080056

setantfltmask

This command allows you to enable or mask the GPS antenna fault. Parameter for this command iseither MASKED or ENABLED. Setting this command to MASKED will prevent the antenna fault
from creating an alarm condition. Some installations may need to mask this fault due to special
antenna situations like splitters or DC blocks that confuse the antenna detection circuit. The factory
default setting is ENABLED.
Command:setantfltmask MASKED
MeridianII reply: Antenna Fault Mask set to MASKED

setcaldelayThis command starts an interactive utility that allows you to change the clock calibration delay. Thissetting is used to advance or retard the clock in order to compensate for antenna cable length or otherexternal hardware or cabling. See Appendix E - Installing the GPS Antenna, Calibrate Your Receiver for more details.
Command:setcaldelay
MeridianII reply: Interactive utility is started.

setgpsdynmode

This command accepts a single argument: ON or OFF, to allow you to set the dynamic mode of operation of the GPS Subsystem. By default, the unit is configured for static operation, so this setting isOFF. It is important that the dynamic mode be set OFF when the instrument is in a static installation.

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If Meridian II will be mounted on a moving platform then this setting must be changed to ON. Thechange takes place immediately and is stored non-volatilely. Dynamic mode is intended for shipboard applications only.
Command:setgpsdynmode ON
MeridianII reply: GPS Dynamic Mode is ON

setgpsrefpos

This command starts an interactive utility that allows you to set the accurate reference position of
Meridian II This utility must be run as the root user. By default, the unit is configured to locate itself
using the GPS satellites. In some situations, visibility of the sky is limited and Meridian II will not
be able to determine its position. In this case, you must determine an accurate WGS-84 position byother means and input it using this command. Changes you make to the position take place immediately. Refer to Appendix E - Installing the GPS Antenna, GPS Reference Position for details. If
the GPS dynamic mode setting is ON (see gpsdynmode/setgpsdynmode commands), then running
this utility will have no effect.
In addition to setting a new reference position, you can also invalidate an existing one. We recommend you do this if Meridian II has an established position and then you move your GPS antenna.
You can invalidate an old position by setting the position mode to UNKNOWN. This will speed up
the time it takes for Meridian II to acquire a new position and relock to the GPS signal. A cold startin unknown position mode should take about 20 minutes to lock, assuming a decent antenna installation.
Command:setgpsrefpos
MeridianII reply:Interactive utility is started.

setinhibitoutputsmodeThis command allows you to set the inhibit mode of the timing outputs. Timing outputs are pulse
rates and time codes. If it is set to ON, then all timing outputs will be inhibited (not present) until thesystem is locked to the GPS signal. If it is set to OFF, then all timing outputs will be present on therear panel at all times. This command requires one argument: ON or OFF.
Command:setinhibitoutputsmode ON
MeridianII reply: Inhibit Outputs Mode is ON

setpwrfltmask (Optional)

See Chapter 10 - Rear-Panel I/O, Masking Dual Power Supply Fault Alarms for information on
this command.

setrticmode (Optional)

This command is only available if the RTIC option has been installed. Refer to Chapter 11 - RealTime Ionospheric Corrections for more information.

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setsigfltmask

This command allows you to enable or mask the Signal Loss Fault. Parameter for this command iseither MASKED or ENABLED. Setting this command to MASKED will prevent a signal loss fault
from creating an alarm condition. Some installations may need to mask this fault when operating the
NTP server as a Stratum 2 server. The factory default setting is ENABLED.
Command:setsigfltmask MASKED
MeridianII reply: Signal Loss Fault Mask set to MASKED

settfomfltlvl

This command allows you to change the TFOM Fault Level. This is the threshold at which a signal
loss fault will be asserted. See Appendix A - Time Figure of Merit for more information. By changing the TFOM Fault Level you control the point at which the time error will produce a signal loss
fault, which then creates an alarm condition. The factory default setting is 9, which is the maximum
TFOM value.
Command:settfomfltlvl 6
MeridianII reply: TFOM Fault Level set to 6

sigfltmask

This command displays the current setting for the Signal Loss Fault Mask.
Command:sigfltmask
MeridianII reply: Signal Loss Fault is ENABLED

subsysreset

This command performs a GPS Subsystem reset which is similar to cycling the power on the GPS
Subsystem. After about 10 seconds, the boot messages from the GPS Subsystem will be displayed.
Command:subsysreset
MeridianII reply:
Bootloader 6010-0070-000 v 1.00 - Dec 27 2012 14:48:55
FW 6010-0076-000 v 1.00 - Jul 12 2015 16:08:46
FPGA 6020-0016-000 v 01
Wait 13 seconds while resetting GPS receiver...

syskernel

This command returns the currently booted linux kernel, either 0 or 1, where 0 is the factory-installedkernel and 1 is the upgraded kernel.
Command:syskernel
MeridianII reply: BOOTED KERNEL IMAGE = 1 (Upgrade)

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sysosctypeThis command displays the installed system oscillator type. It is either TCXO, MS-OCXO, HSOCXO, US-OCXO, Rubidium or US-Rubidium. The standard oscillator type is the TCXO.
Command:sysosctype
MeridianII reply: Installed Oscillator is TCXO.

sysrootfs

This command returns the currently loaded linux root file system, either 0 or 1, where 0 is the factory-installed root file system and 1 is the upgraded root file system.
Command:sysrootfs
MeridianII reply: BOOTED ROOT FILE SYSTEM IMAGE = 1 (Upgrade)sysstatThis command allows you to query the status of the NTP Subsystem. It retrieves information fromthe NTP daemon to determine the current synchronization status of the NTP Subsystem. It thenretrieves the last line in the logfile /var/log/praecis0.monitor controlled by the NTP daemon reference
clock driver that communicates with the GPS Subsystem. This logfile is updated every 16 seconds
under normal operation. It parses and formats the data contained therein and prints this fixed-length(generally, since grossly unsynchronized states could cause the floating offset field to overflow momentarily) string having these fields:
LKSTAT TO GPS, Offset = +S.sssssssss, LI = ??, TFOM = ? @ YEAR DOY HH:MM:SS LS

Where:LKSTATis the system peer status of the NTP daemon relative to the GPS Subsystem, either
LOCKED or NOTLKD. NOTLKD can imply several things: the system has just started,
there is a fault in the GPS Subsystem which has caused NTP to either be unable to obtaintiming information from the GPS Subsystem or to reject the timing information that it isobtaining from it.

+S.sssssssss is the offset in seconds between the NTP system clock and the GPS Subsystem clock.
Positive implies that the system clock is ahead of the GPS Subsystem.
LI = ??

is the NTP daemon leap indicator bits. Leap seconds occur every 2-3 years.
Possible indicator values are:00:
Normal, locked operation.
01:
Leap second insertion event will occur after 23:59:59 UTC.
11:
Fault. Unsynchronized state.

TFOM = ? is a value between 3 and 9 and indicates clock accuracy.
A detailed explanation of TFOM is in Appendix A - TFOM..

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YEAR

is the year of the UTC timestamp of the most recent update received from the GPS Sub
system.

DOY

is the day-of-year of the UTC timestamp of the most recent update received from the
GPS Subsystem.

HH:MM:SS is the hour, minute and second ot the UTC timestamp of the most recent update received
from the GPS Subsystem.
LS

is the current number of leap seconds difference between the UTC and GPS timescales(18 at the time of this writing).

Below is an example of a typical response to this command:
Command:sysstatMeridianII reply:
LOCKED TO GPS, Offset = +0.000000024, LI = 00, TFOM = 4 @ 2013 012 06:03:10 18

systemioThis command returns the current settings for all installed, system-wide I/O signals. These signals
may be routed to CPU Module connectors and/or the optional Plug-In Modules. These signals are
the 1 PPS Output, the Time Code Output, the Direct Digital Synthesizer (DDS) Output and the Serial
Time Output. See Chapter 10 - Rear-Panel I/O for information on the various options.
Command:systemio
MeridianII reply: System I/O Signal 1 PPS OUTPUT is Installed -Current Setting = 1 Milliseconds Pulse Width
System I/O Signal TIME CODE OUTPUT is Installed -Current Setting = IRIG-B122/B002 Format

systemioconfig

This command is an interactive utility that allows the root user to modify the settings for all installed,
system-wide I/O signals. See Chapter 10 - Rear-Panel I/O for information on the various options
and modules.
Command:systemioconfig
MeridianII reply: Interactive shell script is started.

systimemodeThis command displays the current time mode for the front-panel display, the Time Code Output
and the optional Serial Time Output. Time modes are UTC, GPS and LOCAL. The displayed Local Time Offset from UTC and the DST Start/Stop parameters are only valid when the time mode is
LOCAL. A positive Local Time Offset implies a longitude east of the Greenwich meridian and that
Local time is ahead of UTC.

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Command:systimemodeMeridianII reply:
Time Mode = LOCAL
Local Time Zone Offset from UTC (Does Not Include DST) = -16 (half hours)
DST Start Month = Mar Sunday = 2nd Hour = 2
DST Stop Month = Nov Sunday = 1st Hour = 2

systimemodeconfig

This command starts an interactive utility that allows you to configure the time mode of the Time
Code Output, the optional Serial Time output, or the front-panel display of Meridian II. These settings have no effect on the operation of the NTP daemon or the underlying Linux operating systemtime. These ALWAYS operate in UTC.
By default, the unit is configured to operate in UTC mode. If you need to modify the setting, youmust run this utility as root. Settings made using this command are non-volatile.
Command:systimemodeconfig
MeridianII reply: Interactive utility is started.

sysversion

This command displays the firmware version and build date of the Linux root file system.
Command:sysversion
MeridianII reply: Meridian_II GPS 6010-0067-000 v 1.00 - Jan 16 22:38:21 2013

tfomfltlvl

This command displays the current setting for the TFOM fault level.
Command:tfomfltlvl
MeridianII reply: TFOM fault level set to 6

triggerppo (Optional)

This command is only available if one or more Programmable Pulse Output (PPO) options have been
installed. Refer to Chapter 10 - Rear-Panel I/O, Programmable Pulse Output (PPO) Option for
more information.

unlockkp

This command unlocks access to the front-panel keypad EDIT key. When the EDIT key is locked, it
will prevent unauthorized tampering with the unit. All other keys are still enabled so you may continue to read the status and current settings of Meridian. Refer to the kplockstat and lockoutkp
commands.
Command:unlockkp
MeridianII reply: Keypad is UNLOCKED

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updatekernelflag

This command allows you to update the configuration of the Linux bootloader after a new kernel
image has been written to the UPGRADE kernel partition of Meridian II FLASH disk. You may also
use it to reset the default back to the FACTORY kernel partition. Refer to Appendix B - Upgrading
the Firmware, Performing the Linux Kernel Upgrade for detailed instructions for performing the
upgrade procedure. One argument is accepted, whose value is either 0 or 1, which causes a flag to be
set that indicates to the bootloader which kernel image should be loaded by default. If an argument
value of 2 is given, then the currently configured default kernel is shown.
Command:updatekernelflag 1
MeridianII reply: Default Kernel now set to: UPGRADE
Command:updatekernelflag 2
MeridianII reply: Default Kernel = UPGRADE

updaterootflag

This command allows you to update the configuration of the Linux bootloader after a new root filesystem image has been written to the UPGRADE root file system partition of Meridian II FLASH
disk. You may also use it to reset the default back to the FACTORY root file system partition. Refer
to Appendix B - Upgrading the Firmware for detailed instructions for performing the upgrade
procedure. One argument is accepted, whose value is either 0 or 1, which causes a flag to be set thatindicates to the bootloader which root file system image should be loaded by default. If an argument
value of 2 is given, then the currently configured default root file system is shown.
Command:updaterootflag 1
MeridianII reply: Default Root File System now set to: UPGRADE
Command:updaterootflag 2
MeridianII reply: Default Root File System = UPGRADE

upgradekernelThis utility allows you to upgrade the Linux Kernel. It is run after the kernel.gz file has been copied
to the /tmp directory on the system. It performs an erase of the upgrade kernel partition and thenwrites the /tmp/kernel.gz file to it. Refer to Appendix B - Upgrading the Firmware, Performing theLinux Kernel Upgrade for detailed information.
Command:
upgradekernel
MeridianII reply: Shows progress indicator.

upgradercvr

This utility allows you to upgrade the GPS Receiver firmware. Prior to executing this command, youmust copy the new binary firmware file to /tmp/rcvr.bin.
The utility starts the X-modem file transfer, and then displays progress to the console. See Appendix
B - Upgrading the Firmware, Performing the GPS Receiver Upgrade for more information.

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Command:
upgradercvr
MeridianII reply: Upgrade progress is shown.

upgradercvrfpga

This utility allows you to upgrade the Field-Programmable Gate Array (FPGA) resident on the GPS
Receiver. Prior to executing this command, you must copy the new binary file to /tmp/rcvrfpga.bin.
The utility starts the X-modem file transfer, and then displays progress to the console. See Appendix
B - Upgrading the Firmware, Performing the GPS Receiver FPGA Upgrade for more information.
Command:
upgradercvrfpga
MeridianII reply:Upgrade progress is shown.

upgraderootfs

This utility allows you to upgrade the Linux Root File System. It is run after the rootfs.gz file has
been copied to the /tmp directory on the system. It performs an erase of the upgrade root file system
partition and then writes the /tmp/rootfs.gz file to it. Refer to Appendix B - Upgrading the Firmware, Performing the Linux RFS Upgrade for detailed information..
Command:
upgraderootfs
MeridianII reply: Shows progress indicator.

upgradesubsys

This utility allows you to upgrade the GPS Subsystem firmware. Prior to executing this command,
you must copy the binary firmware file to be uploaded to the GPS Subsystem to /tmp/subsys.bin.
It issues the commands over the serial port to the GPS Subsystem that are needed to start the Xmodem file transfer, and then displays progress to the console. See Appendix B - Upgrading the
Firmware, Performing the GPS Subsystem Upgrade for more information.
Command:
upgradesubsys
MeridianII reply: Upgrade progress is shown.

wrt_sw_opt

See Appendix I - Software Options for information on this command.

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"Smarter Timing Solutions"

Chapter FourHyper Text Transfer Protocol Secure (HTTPS)
This chapter briefly describes the HTTPS interface that resides on the Meridian II Precision TimeBase. The HTTPS interface to Meridian II is a fast and easy-to-use graphical interface that is compatible with your standard web browser. Simply point your browser to the IP address of Meridian II
and log in securely with HTTP over the Secure Socket Layer (SSL). Security-conscious customers
may disable the HTTPS interface (see the end of this chapter for instructions).
The HTTPS implementation in Meridian II uses HTTP over SSL. SSL is a sublayer under standard
HTTP. HTTPS enhances security because it encrypts and decrypts the requested and returned pages
from the server, including any passwords which are transmitted.
The HTTPS implementation is built from the standard Apache/2.4.10 distribution from:httpd.apache.org
See Chapter 5 - Security, HTTPS for information on changing the default HTTPS configuration and
SSL certificate and key.

IMPORTANT
A domain name server IP address is required by the Apache web server. When using netconfig (seeChapter 3 - Console Port Control and Status) to configure the TCP/IP parameters, be sure toconfigure a name server. Only one name server is required but two gives some redundancy. The HTTPSInterface will not operate properly if this is configured incorrectly.

47

Meridian II User ManualCHAPTER FOURHTTPS Interface
Description

For security reasons the web pages on Meridian II show status and configuration information only.
You cannot change any operational settings, however you can perform upgrades to Meridian II firmware, which is done with several security measures in place. To make other changes to Meridian II
you will need to use the command line interface via either a network or serial port.

NOTE
For proper operation, your web browser must be configured to allow pop-up windows.

To get started with the web interface simply point your browser to the IP address of Meridian II andlog in securely with HTTPS. Following are examples for IPv4 and IPv6:
IPv4:
IPv6:

http://192.168.1.1
http://[fe80:0:0:0:20e:f3ff:fe01:1f]

Do not forget the brackets [].

A warning dialog page will be presented for the certificate. Acknowledge the dialog page and theserver will continue to load, protected by SSL. The browser should change from http: to https:, indicating that the page is protected by SSL. To maximize security you should replace the SSL Certificate. See Chapter 5 - Security, HTTPS for details.
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Navigation

The main menu tabs across the top of each webpage allow you to navigate through the status information in Meridian II while links on the left side of each webpage provide subcategory navigation.
For example, in the page below the main menu tabs are: Home, Receiver, Plots, Clock, I/O, Faults,
Network, NTP, PTP and Firmware. The tabs across the top and the left-side links are logically arranged for easy navigation.

Page Descriptions

Home: Overall Status Page

Data fields for this page are described below.
Overall Status
Model

Meridian II

Serial Number

Serial number of the Meridian II.

UTC Time,
UTC Date

The current UTC date and time is shown. This date will show year 1980 if
the time has not yet been acquired.

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ReceiverThis is the locked status of the GPS Subsystem/Receiver as follows:
WARMUP:
Warmup period for units with oscillator upgrades.
ACQUIRING: Acquring. Searching for a signal.
LOCKING:
Locking to the GPS signal.
LOCKED:
Locked. Fully synchronized to signal.

TFOMShows the current TFOM value. See Appendix A - TFOM for more
information.

System Status

This field indicates whether a system fault exists. Possible values are OK and
FAULT. If it shows FAULT then go to the Faults Page to see which particularfault is the problem.

CPU Statistics
Current CPU temperature, CPU free memory and CPU load average are all shown.
Home: Front Panel Page
All settings related to the front-panel keypad and display are shown on this page.
Front-Panel Keypad and Display Configuration
Hour Display
This field defines whether the front-panel display shows time in 12 hours
Mode(AM/PM) or 24 hours. It can only be changed via the front-panel keypad/
display. Navigate to Clock Menu > Hour_Mode.
Keypad Lockout

Changing the settings for the Keypad Lockout is done using console portcommands: lockoutkp and unlockkp.

Screen Saver

This setting can only be changed via the front-panel keypad. After a period of
no use, screensaver mode will change the display intensity to half of its
intensity setting.

Display Intensity

This setting can only be changed via the front-panel keypad. Display intensity
settings range from 12% to 100%.

Home: User ManualThis link provides access to the Meridian II User Manual that is resident in the FLASH memory. The
most recent version of the User Manual is on the EndRun website at:
endruntechnologies.com/pdf/USM3043-0000-000.pdf
Home: Logout
Clicking on this link will immediately log you out of the Meridian II HTTPS Interface.

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Plots Page

Information available on this page are statistics related to the GPS Receiver. Links on the right giveaccess to the daily plot files - going back up to 10 years. Links on the left give access to performancestatistics for CPU, Receiver, NTP, and Oscillator. (If your unit has the RTIC Option, then an Ionosphere plot is also available). A sample data plot is shown below:

There are four or five types of data plots available for viewing: CPU, Receiver, NTP, Oscillator andIonosphere (if RTIC Option enabled). The large data plot shown on any of the plot pages is the last
data plot viewed. This could be from any one of the data types (CPU, Receiver, NTP, Oscillator,
Ionosphere).
All plot files are kept in directories. There is one directory for each week. To choose a new plot toview, use the selections on the right side of the page. First, click to select a directory. Then you caneither click to select one of the listed plot files, or you can use your mouse to hover over one of theplot files. Hovering over a plot file will display a small plot next to the large main plot. In this way
you can compare plots from different types to correlate data. For example, you can compare an NTP
data plot with a CPU data plot.
Plots files can also be downloaded from Meridian II as .PNG files. They can be found in the directory /logs/png.

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Receiver: Receiver Page

This page contains information related to the GPS Subsystem/Receiver. Data fields are described
below.
Subsystem Status
State

TFOM

Shows the current state of the GPS Subsystem.
WARMUP:
Warmup period for units with oscillator upgrades.
ACQUIRING: Acquring. Searching for a signal.
LOCKING:
Locking to the GPS signal.
LOCKED:
Locked. Fully synchronized to signal.
Shows the current TFOM value. See Appendix A - TFOM for more
information.

GPS Receiver Status
State
Shows the current state of the GPS Receiver.
WARMUP:
Warmup period for units with oscillator upgrades.
ACQUIRING: Acquring. Searching for a signal.
LOCKING:
Locking to the GPS signal.
LOCKED:
Locked. Fully synchronized to signal.
Satellite ID

This field lists the satellites that are currently being tracked. Up to 12 may be
tracked at a time. Click on the Satellite-Info link for details.

AGC

Automatic Gain Control DAC. Typical value is 150 to 200 in good signal
conditions.

Average C/No

The carrier-to-noise ratio is an indicator of the GPS signal quality.
This number typically ranges from 39 to 50 dB when Meridian II is locked.

GPS Dynamic
ModeThis field shows whether the dynamic mode is set or not. Dynamic mode shouldbe OFF when Meridian II is in a static (not moving) position. To change thedynamic mode setting use the gpsdynmode command.

WGS-84 Reference Position
Position Source
The source of the reference position can be:
UNK:
Unknown position.
DYN:
Dynamic. Position determined while in Dynamic Mode.
USR:
User-entered reference position.
AVG:
Average is a 24-hour average of GPS fixes.
To change the reference position source use the gpsrefpos command.
Latitute,
Longitude,
Height

The WGS-84 latitude and longitude in degrees, minutes and seconds format,
and the height above the WGS-84 reference ellipsoid in meters is shown.
Refer to Appendix D - Installing the GPS Antenna, About WGS-84.

RMS PDOP,
Average CountThe current RMS PDOP of the average position and the current count of
averages are shown. If the reference position source is not AVG, then these twovalues will be zero.

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WGS-84 Last Position Fix
Latitude,
These fields show information for the most recent position fix. The WGS-84
Longitude,
latitude and longitude in degrees, minutes, seconds format and the height above
Heightthe WGS-84 reference ellipsoid in meters is shown. Refer to Appendix D Installing the GPS Antenna, About WGS-84.
PDOP, HDOP,
VDOP, TDOP

DOP stands for Dilution-of-Precision.

Out-of-RangeCount

The out-of-range counter may be non-zero when Meridian II has been moved
more than 1 km from its previous location without being placed in UNKNOWN
mode. (See the setgpsrefpos command.)

GPS-UTC Almanac Info
These fields show the IS-GPS-200 almanac parameters which are used to relate GPS time to UTC.
LS, LSF

These fields contain the current leap second and future leap second values.

WNLSF, DN

These fields show the GPS week number and day number of week at the end ofwhich the future leap second will take effect. This could be in the past if a leap
second insertion has recently taken place. Leap second events occur every few
years on either June 30 or December 31.

A0, A1,
WNt, tot

These fields show the parameters for calculating the small residual offset
between the GPS master clock ensemble and UTC(USNO). This is typicallyless than 10 nanoseconds.

Current(GPS-UTC)

This is the current value of the GPS-UTC offset, which includes leap seconds
plus the small residual offset explained above. Time and date of most recently
received satellite transmission containing this data is also shown.

GPS Ionosphere Almanac Info
The information shown here is the broadcast GPS almanac parameters for the Klobuchar ionosphericdelay model. Two sets of model parameters are shown. The first (alpha) is the most recently received
set. The second (beta) is the previously received set. The GPS week number and time of week arealso shown.
Real-Time Ionospheric Corrections (Optional)
This section is for the optional RTIC. If your Meridian II does not have RTIC, then this section will
not be shown. For more information on RTIC see Chapter 11 - Real-Time Ionospheric Corrections.
Configuration
Clock Calibration

53

Clock calibration is used to advance or retard the clock in order to correct for
GPS Receiver delay and any propagation delay due to GPS antenna cable.
It may also be used to compensate for the inherent time offsets that may exist
with external hardware such as distribution amplifiers, etc. Calibration range is±500,000 nanoseconds.

Meridian II User ManualCHAPTER FOUR

Receiver: Oscillator Page
This page shows system oscillator control information for the GPS Subsystem:
Oscillator Status
Oscillator Type

This field shows the system oscillator type that is installed in Meridian II. It
will be either TCXO (standard), or the optional MS-OCXO, HS-OCXO,
US-OCXO, Rubidium or US-Rubidium.

DAC

The system oscillator control DAC value indicates the frequency control setting.
The system automatically sets this value to remove frequency errors. Values
may range from 0 to 1,048,575. Values close to the minimum or maximum will
set the DAC fault flag.

MeasuredTime Error

This field shows the last measured time offset of the GPS Subsystem relative to
GPS while locked, in second.

Time Deviation

This field shows the time deviation (TDEV) of the offset measurements inseconds. The tau associated with this measurement is one second, which is the
update interval of the position fixes received from the GPS Receiver.

Oscillator
Ageing Rate

This field shows the regression-computed system oscillator ageing rate per day(several-hours delay before the first measurements are displayed).

Control Loop TAU This field shows the system oscillator control loop averaging time constant, inseconds. It’s value is automatically adjusted to maintain optimum offset andstability.
Coast Duration

This shows the number of seconds the GPS Subsystem has been in coast mode,
while Meridian II is unlocked to GPS. Coast mode is another term for holdovermode.

Estimated Time
Error

This is the estimated time error of the GPS Subsystem when in coast/holdovermode, in seconds.

Internal Chassis
Temperature

Internal chassis temperature in °C. Available with OCXO or Rubidium
oscillators.

Clock Page

This page shows the configuration of the Meridian II Precision TimeBase except for any optional I/O
which is listed on the I/O page.
Clock Configuration
Time Mode
This field shows the current time mode setting. Possible settings are UTC, GPS
and Local. Since NTP always uses UTC, this setting only affects the frontpanel display and any optional Time Code or Serial Time outputs. For example,
if this field shows Local, then the time shown on the front-panel display will be
Local time but NTP will remain at UTC time. To change the time mode setting
use the systimemodeconfig command via the console port.
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Time Zone
OffsetThis field shows the offset from UTC and is only valid when the Time Mode is
Local. A positive Time Zone Offset implies a longitude east of the Greenwich
meridian. To change the time zone use the systimemodeconfig command.

Daylight Saving
TimeThis field will show whether DST control is enabled or not.
DST fields are only used when the Time Mode is Local.

DST Start,
DST End

These fields will only display if the Daylight Saving Time field above shows
enabled. If enabled, then these fields show when DST starts and ends during theyear. For example, in most of the U.S.A. the DST Start Time is the 2nd Sundayin March at 2 a.m. The DST End Time is the 1st Sunday in November at 2
a.m. DST settings are used when the time mode is Local. To change the DST
settings use the systimemodeconfig command.

I/O PageThis page shows the CPU Module outputs and their settings. The standard outputs are the 1 PPS andTime Code (AM). There may also be one optional output for the 1U chassis, or four optional outputs
for the 2U chassis. Use commands cpuoptsconfig and sysioconfig via the console port tochange the settings of the CPU Module outputs. See Chapter 10 - Rear-Panel I/O for information on
the various options.
I/O Page (Plug-In Options)This page shows any installed Plug-In Modules and their settings. Some plug-in modules can beuser-configured. Use command pluginoptsconfig to change the configuration of these modules.

Faults: System Faults Page

This page lists all possible system fault conditions of Meridian II - the Linux Subsystem, the GPS
Subsystem and the GPS Receiver. For details on each fault see Appendix G - System Faults.
Faults: Fault Mask Page
Fault Masks
Signal Fault
This field shows the current mask setting for the Signal Fault, either Masked or
Enabled. When the signal fault is Masked it will prevent a Signal Loss Fault
from occurring. Some installations may need to mask this fault when operating
Meridian II with no GPS signal. (An example of this would be when
configured as a Stratum 2 NTP Server.) To change the Signal Fault Mask use
the setsigfltmask command, or the front-panel keypad/display.
Antenna Fault

55

This field shows the current mask setting for the Antenna Fault. When theantenna fault is Masked it will prevent an Antenna Fault from occurring.
Some installations may need to mask this fault due to special antenna situations
like splitters. To change the Antenna Fault Mask use the setantfltmask
command, or the front-panel keypad/display.

Meridian II User ManualCHAPTER FOUR

Primary andSecondary Power
Fault Alarms

These fields will display ONLY if your Meridian II has the Dual Power Supply
option installed. See Chapter 10 - Rear Panel I/O, Masking Dual Power
Supply Fault Alarms for more information.

Faults: TFOM Fault Level Page
This is the threshold at which a signal loss fault will be asserted. See Appendix A - Time Figure of
Merit for more information. You can change the TFOM Fault Level by using the settfomfltlvl
command. The factory default setting is 9, which is the maximum TFOM value.
Faults: Receiver Faults Page
This page lists all possible system fault conditions of the GPS Receiver. For details on each fault see
Appendix G - System Faults.

Network: IPv4 Page

This page shows the IPv4 network configuration.
IPv4 Network Status
DHCP
By default, Meridian II will configure itself using the Dynamic Host
Configuration Protocol (DHCP). If you need to set up static IP configuration,
you must use the netconfig command via the console port. Thie field willshow whether DHCP is enabled or disabled.
Address, Gateway
Netmask

These fields show the settings for the IP address, gateway and netmask.
To change these settings use the netconfig command via the console port.

Network: IPv6 Page
This page shows information related to the IPv6 network parameters. For more information on IPv6
see Chapter 8 - IPv6 Information.
Network: DNS Page
This page shows the IP addresses of the primary and secondary domain name servers.
Network: MAC Address Page
This page shows the media-access-control (MAC) address for both Ethernet ports (eth0 and eth1).

NTP Page

The NTP Status page shows all information related to NTP operation.
NTP Status
Status

56

The stratum field has several possible values:
Stratum 1:
The server is fully synchronized and accurate.
Stratum 2:
The server is synchronized to a Stratum 1 server.
Stratum x:
The server is synchronized to a Stratum x-1 server.
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Stratum 16:

The server is unsynchronized. NTP clients will not use aStratum 16 server.

SourceThis field will show the source of time which is usually GPS. If Meridian II isconfigured as a Stratum 2 server then it will show the IP address of the
upstream Stratum 1 server.

OffsetThis field shows the offset in seconds between the NTP system clock and the
GPS Subsystem clock. Positive implies that the NTP system clock is ahead of
the GPS Subsystem clock.

Leap Indicator
Bits

This field shows whether a leap second is pending. Leap second events occur
approximately every 2-3 years as announced by the International Earth Rotation
and Reference Systems Service (IERS). Possible indicator values are:00:
Normal, locked operation.
01:
Leap second insertion event will occur after 23:59:59 UTC.
11:
Fault. Unsynchronized state.

I/O Statistics
Time Since Reset, These fields show statistics accumulated since the last reboot of the system.
Packets Sent/Received,
Packets Sent Rate,
Packets Dropped

PTP: Status and Configuration Pages (Optional)

The fields on these pages show the status and the configuration for the optional PTP/IEEE-1588 protocol. If your Meridian II does not have PTP enabled then there will be no fields shown. For more
information on PTP and an explanation of the data fields on this page see Chapter 4 - PTP/IEEE1588.

Firmware: Firmware Status Page

The firmware status page shows part numbers and revisions for Meridian II firmware components
which are: Linux Root File System (RFS), Linux Kernel, GPS Subsystem, GPS Subsystem FPGA
and GPS Receiver. Meridian also has two Field-Programmable Gate Arrays which are: GPS Subsystem FPGA and GPS Receiver FPGA.
Firmware: Linux RFS Upgrade Page
This page is used for upgrading the Linux RFS firmware. You must be logged in as “root” in order tohave access to this page. The latest released versions of Meridian II firmware are freely available on
the EndRun Technologies website. For detailed information on how to perform the upgrade either via
the network port, the serial port, or the HTTPS interface see Appendix B - Upgrading The Firmware.

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Firmware: Linux Kernel UpgradeThis page is used for upgrading the Linux Kernel firmware. You must be logged in as “root” in orderto have access to this page. The latest released versions of Meridian II firmware are freely available on the EndRun Technologies website. For detailed information on how to perform the upgrade
either via the network port, the serial port, or the HTTPS interface see Appendix B - Upgrading The
Firmware.
Firmware: GPS Subsystem Upgrade Page
This page is used for upgrading the firmware. You must be logged in as “root” in order to have access to these pages. The latest released versions of Meridian II firmware are freely available on the
EndRun Technologies website. For detailed information on how to perform the upgrade either via the
network port, the serial port, or the HTTPS interface see Appendix B - Upgrading The Firmware.
Firmware: GPS Receiver Upgrade Page
This page is used for upgrading the firmware for the GPS Receiver. You must be logged in as “root”
in order to have access to these pages. The latest released versions of Meridian II firmware are freely
available on the EndRun Technologies website. For detailed information on how to perform the upgrade either via the network port, the serial port, or the HTTPS interface see Appendix B - Upgrading The Firmware.
Firmware: Reboot Page
This page will allow you to perform a software reboot of both the Linux Subsystem and the GPS
Subsystem. This is normally used after a firmware upgrade but can be done anytime you wish toreset the Meridian II.

Disable or
Restrict AccessTo disable HTTPS, see Chapter 5 - Security, Disable SNMP, SSH and HTTPS. To restrict access to
specific hosts see Chapter 5 - Security, Restrict Access - HTTPS.

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Chapter Five
SecurityYour Meridian II Precision TimeBase incorporates several important security features to prevent
unauthorized tampering with its operation. Many of these are standard multiple-user access control
features of the underlying Linux operating system which controls the Meridian II. Others are provided by the additional protocol servers selected for inclusion in your Meridian II, and the way thatthey are configured.
Secure user authentication and session privacy while performing routine monitoring and maintenancetasks are provided by the OpenSSH implementations of the “secure shell” daemon, sshd and its companion “secure copy” utility, scp. The Apache implementation of the Hyper Text Transfer Protocol(HTTPS) with Secure Sockets Layer (SSL) daemon (httpd ) provides for a secure, encrypted session
with a digital certificate. The NET-SNMP implementation of the Simple Network Management
Protocol (SNMP) daemon, snmpd conforms to the latest Internet standard, known as SNMPv3, which
also supports secure user authentication and session privacy. In addition, the Network Time Protocol daemon, ntpd supports client-server authentication security measures to deter spoofing of NTP
clients by rogue NTP servers. This chapter describes these security measures and gives the advanced
network administrator information that will allow custom configuration to fit specific security needs.

IMPORTANT
SSH, Telnet, SNMP and HTTPS are all enabled with default passwords. To ensure security, change thepasswords or disable the protocols. To change the passwords for SSH, Telnet and HTTPS use the passwd
command. To change the passwords/community strings for SNMP see Chapter 6 - SNMP.
By default all hosts are allowed access via SSH, Telnet and SNMP. To restrict access via these protocols to
specific hosts, see Restrict Access - Telnet, SSH and SNMP below. All hosts are allowed access via
HTTPS as well. To restrict access via HTTPS, see Restrict Access - HTTPS below.
To completely disable any or all of these protocols see Disable Protocols below.

Linux Operating System

The Linux operating system versions are shown in Appendix K - Specifications. Linux supports acomplete set of security provisions:• System passwords are kept in an encrypted file, /etc/shadow which is not accessible by users otherthan root.

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• Direct root logins are only permitted on the local RS-232 console or via SSH.
• The secure copy utility, scp, eliminates the need to use the insecure FTP protocol for transferring
program updates to Meridian II.
• ΗTTP access for system monitoring only, is allowed only via SSL, so passwords and session data
are encrypted on the wire. Access via HTTPS may be restricted or completely disabled. See Restrict
Access - HTTPS and Disable SNMP, SSH and HTTPS below.
• SNMP access for system monitoring only, is configurable to provide the security of the latest version 3 Internet standard which supports both view-based access control and user-based security using
modern encryption techniques. Previous versions v1 and v2c supported access control essentially
via passwords transmitted over the network in plain text. Refer to Chapter 6 - SNMP and Restrict
Access - Telnet, SSH and SNMP (below) for details. SNMP may also be completely disabled. See
Disable SNMP, SSH and HTTPS below.
• Individual host access to protocol server daemons in.telnetd, snmpd or sshd are controlled bydirectives contained in the files /etc/hosts.allow and /etc/hosts.deny, which are configured using theinteractive script accessconfig. See Restrict Access - Telnet, SSH and SNMP below.
• Insecure protocols like Time, Daytime and Telnet may be completely disabled by configuration of
the inetd super-server daemon using the interactive script inetdconfig. See Disable Telnet, Timeand Daytime below.

Restrict Access

The following paragraphs describe how to restrict SNMP, SSH, Telnet and HTTPS access to specifichosts. Also described is how to restrict NTP query access.

Restrict Access - Telnet, SSH and SNMP

By default, Meridian II is configured to allow access by all users via Telnet, SSH and SNMP. To
ensure security and to protect against denial-of-service attacks, you should restrict access by using theaccessconfig command.
accessconfig modifies two files, /etc/hosts.allow and /etc/hosts.deny, which are used by tcpd andthe standalone daemons, snmpd and sshd, to determine whether or not to grant access to a request-

ing host. These two files may contain configuration information for a number of protocol servers, but
in Meridian II only access control to the protocol server daemons in.telnetd, sshd and snmpd isconfigured.
As shipped from the factory, these two files are empty. When you run accessconfig, these lines
are added to the /etc/hosts.deny file:in.telnetd:
sshd: ALL
snmpd: ALL

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This tells tcpd to deny access to in.telnetd, sshd and snmpd to all hosts not listed in the /etc/
hosts.allow file. The snmpd and sshd daemons also parse this file directly prior to granting access toa requesting host.
Next you will be prompted to enter a list of hosts that will be granted access to in.telnetd, sshd
and snmpd. These appear in the /etc/hosts.allow as lines like this:in.telnetd: 192.168.1.2, 192.168.1.3
sshd: 192.168.1.2, 192.168.1.3
snmpd: 192.168.1.2, 192.l68.1.3

This simple shell script handles the needs of most users, however the syntax of these two files supports elaborate configuration possibilities which are beyond the capabilites of this simple shell script.
Advanced users who need these capabilities will need to edit these two files directly and then copy
them to the /boot/etc directory. (See Appendix C - Helpful Linux Information, Using Editors.) Be
careful to maintain the proper ownership and access permissions by using cp -p when copying thefiles.

Restrict Access - HTTPS

To control access via HTTPS, you must edit the /etc/httpd/httpd.conf file and add the equivalent denyfollowed by allow directives. For example, the default file contains these lines:<Directory “srv/httpd/cgi-bin”>
AllowOverride None
Options None
Require all granted</Directory>

To complete the configuration steps to restrict access and allow a specific host with IP address
xxx.xxx.xxx.xxx, you would modify the directives as follows:<Directory “srv/httpd/cgi-bin”>
AllowOverride None
Options None
Require ip xxx.xxx.xxx.xxx# Require all granted</Directory>

After making and saving your changes, you must copy the edited file to the non-volatile FLASH area
and reboot the unit:
cp -p /etc/httpd/httpd.conf /boot/etc/httpdreboot61

Meridian II User ManualCHAPTER FIVE

Restrict Query Access - NTP

The Network Time Protocol (NTP) implementation in Meridian II is built from the reference distribution from:http://www.ntp.org
By factory default, remote control and query of the NTP daemon ntpd is disabled. Query-onlyoperation is supported only from processes running on Meridian II itself, i.e. from the localhost. This
restricts access to ntpd from remote hosts using either of the two NTP companion utilities ntpq and
ntpdc.
Control via these two utilities is disabled in the /etc/ntp.conf file in two ways. First, MD5 authentication keys are not defined for control operation via a requestkey or controlkey declaration. Second,
this default address restriction line is present in the file:
restrict default nomodify noquery nopeer
restrict 127.0.0.1 nomodify
restrict 0::1 nomodify

The first line eliminates control and query access from ALL hosts. The second and third lines disable
the localhost from making any modifications to the ntpd daemon, but query access is not affectedby this restriction. These lines must not be removed, as they are necessary for various monitoringprocesses running on Meridian II to function properly.
Knowledgable NTP users who would like to customize the security aspects of the configuration of the
NTP daemon in Meridian II should edit the /etc/ntp.conf file directly and then copy it to the /boot/etc
directory. Be sure to retain the ownership and permissions of the original file by using cp –p when
performing the copy.

CAUTION
If you are planning to make changes to the /etc/ntp.conf file, you must NOT restrict query access fromthe local host to the NTP daemon. Various system monitoring processes running on the system require thisaccess.
An example follows which shows how to allow query access from a specific remote host with IP
address 192.168.1.10 while also allowing processes running on Meridian II to have query access as
well:
restrict default noquery nomodify nopeer
restrict 127.0.0.1 nomodify
restrict 0::1 nomodify
restrict 192.168.1.10 nomodify

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Disable Protocols

See below for instructions on how to completely disable the following protocols: Telnet, Time, Daytime, SSH, SNMP, and HTTPS. See Chapter 9 - PTP/IEEE-1588 Option for how to disable PTP.
The Network Time Protocol (NTP) cannot be disabled.

Disable Telnet, Time and Daytime

To disable Telnet, Time and Daytime use the inetdconfig command to start an interactive scriptthat will ask you which protocols to disable. Then it will modify the /etc/inetd.conf file, which is readby the super-server daemon, inetd. Requests from remote hosts for protocols not configured in /etc/
inetd.conf will be refused. Currently, three servers are configurable via inetdconfig: Time andDaytime (whose protocol servers are contained within the inetd daemon itself), and in.telnetd.
Any one or all of these may be enabled or disabled for start-up.

Disable SNMP, SSH and HTTPSTo disable SNMP, SSH or HTTPS, you only have to modify the file mode of the scripts that control
their execution. These are located in the /etc/rc.d directory.To disable any of these daemons, issue
one or more of these commands:
chmod -x /etc/rc.d/rc.snmpd
chmod -x /etc/rc.d/rc.sshd
chmod -x /etc/rc.d/rc.httpdAfter issuing these commands, you must copy the modified file(s) to the non-volatile FLASH area
using one or more of these commands:
cp -p /etc/rc.d/rc.snmpd /boot/etc/rc.d
cp -p /etc/rc.d/rc.sshd /boot/etc/rc.d
cp -p /etc/rc.d/rc.httpd /boot/etc/rc.d

Reboot Meridian II when done for the changes to take effect.

IMPORTANT
After modifying /etc/rc.d/rc.snmpd, rc.sshd or rc.httpd, you must copy them to the /boot/etc/rc.ddirectory and reboot the system. It is very important to use the -p when performing the copy. During theboot process, the files contained in the /boot/etc/rc.d directory are copied to the working /etc/rc.d directory on the system RAM disk. In this way the factory defaults are overwritten.

Re-Enable SNMP, SSH and HTTPS

If you have disabled SNMP, SSH or HTTPS, and you want to re-enable it, all you need to do is remove the rc file from the /boot/etc/rc.d directory using one or more of these commands:
rm /boot/etc/rc.d/rc.snmpd
rm /boot/etc/rc.d/rc.sshd
rm /boot/etc/rc.d/rc.httpd63

Meridian II User ManualCHAPTER FIVE

Reboot Meridian II when done for the changes to take effect.

Is the Protocol Disabled?

Telnet, TIME and DAYTIME: To determine if one of these protocols is disabled, use the inetdconfig command.
SNMP, SSH and HTTPS: To determine if one of these protocols is disabled, issue the following
command:ls -l /boot/etc/rc.d

If you see one of the following files listed, and there is NOT an ‘*’ after the file name, then the corresponding protocol is disabled:-rw-r--r-- 1 root root 1144 Feb 19 01:52 rc.httpd-rw-r--r-- 1 root root 1168 Oct 26 2012 rc.snmpd-rw-r--r-- 1 root root 2684 Feb 18 02:16 rc.sshd

If rc.httpd, rc.snmp, or rc.ssh is not listed, or it is listed and there is an ‘*’ after the file name, then the
protocol is enabled. Here is an example:-rwxr-xr-x 1 root root 1168 Oct 26 2012

OpenSSH

rc.snmpd*

The secure shell protocol server running in Meridian II is based on the portable OpenSSH for Linux.
As such it supports both SSH1 and SSH2 protocol versions. By default, only SSH2 is enabled in
Meridian II due to security issues with SSH1. For more information about OpenSSH, and to obtainclient software, refer to the OpenSSH website:
openssh.com
An excellent book which describes operation and configuration of the various SSH implementations,
including OpenSSH is:
SSH, The Secure Shell, Barrett & Silverman, O’Reilley & Associates, 2001.
NOTE: To disable the SSH protocol see Disable SNMP, SSH and HTTPS above. To restrict accesssee Restrict Access - Telnet, SSH and SNMP above.

Configure Keys

On initial boot-up from out-of-the-box, the SSH start-up script, /etc/rc.d/rc.sshd, will detect that no
keys are present in the /etc/ssh directory. It will call ssh-keygen to generate a set of host keys andthen it will copy them to the /boot/etc/ssh directory. These will be copied to /etc/ssh during each bootup. A complete set of security keys for both SSH1 and SSH2 versions of the protocol are generated.
RSA keys are supported by both versions, and DSA keys are supported when using the SSH2 version.

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Should you need to replace your keys at any time, you can just remove the keys from the /boot/etc/
ssh directory and then reboot Meridian II. A new set of host keys will automatically be generated.
To configure root logins to your Meridian II via passwordless, public key authentication, you must
generate a public/private pair of SSH2 keys using your own ssh key generating utility, or you can use
the ssh-keygen that is resident on Meridian II file system. You must then append the public key tothe /boot/root/.ssh/authorized_keys file in the non-volatile FLASH area on your Meridian II. At boottime, Meridian II will copy these to the actual working /root/.ssh directory of the system ramdisk. To
use this capability, the corresponding private key must reside in the /root/.ssh directory of your remote computer as id_rsa or id_dsa. If you are unfamilar with this process, refer to the man page forthe ssh-keygen utility for details (issue man ssh-keygen at the prompt). (Be careful to maintainthe proper ownership and access permissions of the private key by using cp -p when copying thefile. It MUST be readable only by root.)
Advanced users wishing to modify the overall configuration of the sshd daemon should edit the/etc/ssh/sshd_config file and then copy it to the /boot/etc/ssh directory of Meridian II. Be careful tomaintain the proper ownership and access permissions by using cp -p when copying the file. Atboot time, it will be copied to the /etc/ssh directory of the system ramdisk, thereby replacing the factory default configuration file.

HTTPS

The HTTPS server in Meridian II is built from the standard Apache version 2.4.10 distribution from:httpd.apache.org
It uses HTTPS (HTTP over SSL) with mod_ssl (the Apache interface to OpenSSL). For more information about this protocol, refer to:modssl.org
NOTE: To disable the HTTPS protocol see Disable SNMP, SSH and HTTPS above. To restrict access see Restrict Access - HTTPS above.
HTTPS and SSL use files for the default configuration located in /etc/httpd. Of these, you will typically only need to modify httpd.conf. Advanced users who need to modify the default configuration
will need to edit the file and copy it to the /boot/etc/httpd directory. Do not attempt to change thedirectives unless you have a real need to do so. (See Appendix C - Helpful Linux Information, Using Editors above.)

Configure Certificate and Key

For SSL it is recommended, but not required, that new certificates and keys are generated andinstalled on the Apache web server with mod_ssl. The factory configured, self-signed certificate is
located in /etc/httpd/server.crt, and the key in/etc/httpd/server.key. After creating new certificates andprivate keys, they will need to be saved in /boot/etc/httpd/server.crt and /boot/etc/httpd/server.key. To
generate a new certificate and key, issue these commands:

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Meridian II User ManualCHAPTER FIVE

cd /boot/etc/httpdopenssl req -new -x509 -nodes -out server.crt -keyout server.key

The two files will be created in the /boot/etc/httpd directory. You must reboot Meridian II for themto take effect. An excellent book which describes operation and configuration of the various HTTPS
directives and SSL configuration is:Professional Apache, Wainwright, Wrox Press, 1999.

NTP

Network Security
Vulnerabilities

You can configure your NTP clients for secure MD5 authentication. See Chapter 7 - NTP, Unix-like
Platforms: MD5 Authenticated NTP Client Setup or Chapter 7 - NTP, Windows: MD5 Authenticated NTP Client Setup. You can also restrict NTP query access. See Restrict Query Access - NTP
in this chapter.

EndRun addresses major network security vulnerabilities that affect Meridian II at the top of thiswebpage:endruntechnologies.com/support/product-bulletins
This Application Note describes best practices to secure your time server and mitigate many network
security vulnerabilities:
endruntechnologies.com/pdf/Time-Server-Security-Best-Practices.pdf

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Chapter Six

Simple Network Management Protocol (SNMP)Your Meridian II Precision TimeBase includes the NET-SNMP version 5.5.1 implementation of an
SNMP agent, snmpd, and a SNMP notification/trap generation utility, snmptrap. It supports all
versions of the protocol in use today: SNMPv1 (the original Internet standard), SNMPv2c (neverreached standard status, often called “community SNMP”) and SNMPv3 (the latest Internet standard).
The NET-SNMP project has its roots in the Carnegie-Mellon University SNMP implementation. For
more detailed information about the NET-SNMP project and to obtain management software anddetailed configuration information, you can visit this website:
net-snmp.org
An excellent book which describes operation and configuration of various SNMP managers andagents, including the NET-SNMP implementations, is available from O’Reilley & Associates:
Essential SNMP, Mauro & Schmidt, O’Reilley & Associates, 2001
If you are planning to operate with SNMPv3, it is highly recommended that you make use of both ofthese resources to familiarize yourself with the agent configuration concepts.

SNMPv3 Security

Prior to SNMPv3, SNMP had definite security inadequacies due to using two community names ina manner analogous to passwords that were transmitted over the network as clear text. In addition,
since no mechanism existed for authenticating or encrypting session data, any number of man-inthe-middle data corruption/replacement exploits were possible in addition to plain old snooping tolearn the community names. SNMPv3 implements the User-based Security Model (USM) defined in
RFC-2274 which employs modern cryptographic technologies to both authenticate multiple users andto encrypt their session data for privacy, much in the same way that SSH does for remote login shellusers.
In addition, it implements the View-based Access Control Model (VACM) defined in RFC-2275.
This RFC defines mechanisms for limiting the access of multiple users having various security levels(no authentication, authentication or authentication plus privacy) to specific “views” of the Structureof Management Information (SMI) object tree.

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Meridian II User ManualCHAPTER SIXEnterprise Management
Information Base (MIB)

In addition to providing the SNMP variables contained in MIB-II as described in RFC-1213, EndRun
Technologies has implemented an enterprise MIB using the syntax of the SMI version 2 (SMIv2) as
described in RFC-2578:
Meridian2-MIB
Which is located on your Meridian II in one of these ASCII files:/usr/local/share/snmp/mibs/MERIDIAN2-MIB.txt/usr/local/share/snmp/mibs/MERIDIAN22U-MIB.txt(1U chassis)(2U chassis)

In addition to a complete set of NTP and Receiver (GPS) status objects, the MIB defines four SMIv2
notification objects:••••

Invocation of the
SNMP daemon

NTP Leap Indicator Bits status change
NTP Stratum change
Receiver Fault Status change
Receiver Time Figure of Merit change

The SNMP daemon, snmpd is started from the /etc/rc.d/rc.snmpd system start-up script. By default, it
will listen on port 161 for SNMP queries from the network management system. If you would like tohave it listen on another port, you could edit the file and change the port number in the argument list
being passed to snmpd when it is started.

IMPORTANT
After modifying /etc/rc.d/rc.snmpd, you must copy it to the /boot/etc/rc.d directory and reboot the system. It is very important to retain the access mode for the file, so be sure to use cp -p when performing
the copy. During the boot process, the files contained in the /boot/etc/rc.d directory are copied to theworking /etc/rc.d directory on the system RAM disk. In this way the factory defaults are overwritten.

Quick Start Configuration-- SNMPv1/v2c

You should be able to compile the MERIDIAN2-MIB file on your SNMP management system andaccess the variables defined therein. The factory default community names are “Meridian2” for theread-only community and “endrun_1” for the read-write community. This is all that is required for
operation under v1 and v2c of SNMP.

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Change Default Community Strings (Passwords)

You can, and should, change the default community names by editing /etc/snmpd.conf and modifying
these two lines:
rwcommunity
rocommunity

Configuring SNMPv1
Trap Generation

endrun_1
Meridian2

To have your Meridian II send SNMPv1 traps (RFC-1215) you must configure the community anddestination for SNMPv1 traps by uncommenting and editing this line in /etc/snmpd.conf:
trapsink

xxx.xxx.xxx.xxx trapcommunity trapport

where trapcommunity should be replaced by your community, and xxx.xxx.xxx.xxx is the IP
address or hostname of the destination host for receiving the traps generated by Meridian II. By default, the trap will be sent to port 162. You may optionally add another parameter, trapport to theend of the above line to override the default port setting. Otherwise leave it blank.
Note: Though the agent will recognize multiple trapsink lines within /etc/snmpd.conf and send thegeneric SNMP coldStart or authenticationFailure traps to multiple destinations, the Meridian II enterprise MIB trap generation mechanism will only send a trap to the last declared trapsink in the file.

Configuring SNMPv2c
Notifications and Informs

To have your Meridian II send SNMPv2c notifications (SMIv2, RFC-2578) or informs, you must
configure the communities and destinations by uncommenting and editing one or both of these lines
in /etc/snmpd.conf:
trap2sinkinformsink

xxx.xxx.xxx.xxx trap2community trap2port
xxx.xxx.xxx.xxx informcommunity informportwhere trap2community and informcommunity should be replaced by your communities, andxxx.xxx.xxx.xxx is the IP address or hostname of the destination host for receiving the notifications or informs generated by Meridian II. By default, the v2c trap or inform will be sent to port 162.
You may optionally add another parameter, trap2port or informport to the ends of the abovelines to override the default port setting. Otherwise leave it blank.
Note: Though the snmpd agent will recognize multiple trap2sink or informsink lines within/etc/snmpd.conf and send the generic SNMP coldStart or authenticationFailure notifications and informs to multiple destinations, the Meridian II enterprise MIB notification/inform generation mechanism will only send a notification to the last declared trap2sink, and an inform to the last declared
informsink in the file.

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IMPORTANT
After editing /etc/snmpd.conf, you must copy it to the /boot/etc directory and reboot the system. It isvery important to retain the access mode for the file (readable only by root), so be sure to use cp -p
when performing the copy. During the boot process, the files contained in the /boot/etc directory are copied to the working /etc directory on the system RAM disk. In this way the factory defaults are overwritten.

Configuration of SNMPv3

If you are planning to use SNMPv3, you should definitely make use of the two resources mentioned
previously (NET-SNMP website and Essential SNMP) and study them carefully. There are rather
elaborate configuration options available when you are using v3. The instruction presented here will
give you the flavor of the configuration but definitely not the full scope of possibilities. To accessyour Meridian II via v3 of SNMP, you will have to configure two files:/etc/snmpd.conf/boot/net-snmp/snmpd.conf
The first file contains static configuration parameters that the agent uses to control access and to determine where to send notifications/traps. Other aspects of the agent’s operation are also configurable
in this file, but you should not need to modify those. To use the SNMPv3 capabilities of Meridian II,
you must first set up user information and access limits for those users in /etc/snmpd.conf. Uncomment and edit these two lines to define your v3 users and their access parameters:
rwuser root
priv .1
rouser Meridian2 auth .1.3.6.1.4.1.13827

The first line defines a SNMPv3 read-write user root whose minimum security level will be authenticated and encrypted for privacy (choices are noauth, auth and priv), and who will have read-write access to the entire iso(1) branch of the SMI object tree. The second line defines a SNMPv3 read-onlyuser Meridian2 whose minimum security level will be authenticated but not encrypted, and who will
have read-only access to the entire iso(1).org(3).dod(6).internet(1).private(4).enterprises(1).endRunTechnologiesMIB(13827) branch of the SMI object tree. After adding the user lines to /etc/
snmpd.conf, copy it to the /boot/etc directory using cp –p.
The second file is located on the non-volatile FLASH disk and is used by the SNMP agent to store“persistent data” that may be dynamic in nature. This may include the values of the MIB-II variables
sysLocation, sysContact and sysName as well as any configured SNMPv3 user crypto keys. In order
to use SNMPv3, you must configure user keys in this file for each SNMPv3 user that you have set up
in /etc/snmpd.conf. To do this, you must add lines to /boot/net-snmp/snmpd.conf like these for eachuser:
createUser root
MD5 endrun_1 DES endrun_1
createUser Meridian2 SHA Meridian2_0

The first line will cause the agent, snmpd to create a user root who may be authenticated via Message Digest Algorithm 5 (MD5) with password endrun_1 and may use the Data Encryption Standard(DES) to encrypt the session data with passphrase endrun_1. The second line will cause a user
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Meridian2 to be created who may be authenticated using the Secure Hash Algorithm (SHA) withpassword Meridian2_0. Passwords and passphrases must have a minimum of 8 characters, or you
will not be able to be authenticated.

IMPORTANT
You must kill the snmpd daemon prior to editing, /boot/net-snmp/snmpd.conf. Otherwise, the secretkey creation may not complete properly. Issue the command /etc/rc.d/rc.snmpd stop to kill
the snmpd daemon. You can verify that the snmpd daemon has been killed by issuing the ps -e
command and verifying that it is not present.

After rebooting, the agent will read the /boot/net-snmp/snmpd.conf configuration file and compute
secret key(s) for each of the users and delete the createUser lines from the file. It will then write
the secret key(s) to the file. These lines begin with the string, usmUser. In this way, un-encrypted
passwords are not stored on the system.

IMPORTANTTo generate new keys, stop the snmpd process, delete the existing usmUser key lines from the file/boot/net-snmp/snmpd.conf and then add new createUser lines. Then reboot the system.

This example gives the simplest configuration to begin using SNMPv3 but doesn’t make use of thefull capabilities of the VACM in defining groups and views for fine-grained access control. The factory default /etc/snmpd.conf file contains commented blocks of lines that can be uncommented to give
you a basic configuration that uses the User-based Security Model (USM) described in RFC-2274 andthe View-based Access Control Model (VACM) described in RFC-2275. The comments included in
the file should help you in modifying it for your specific requirements.

Configuring SNMPv3
Notifications and Informs

If you have followed the steps in Configuration of SNMPv3 (above), then you are almost ready to
use SNMPv3 notifications and informs.
SNMPv3 uses the same trap2sink and informsink directives in /etc/snmpd.conf as SNMPv2c.
The difference being that snmptrap requires authorization and authentication information be provided to it when sending SNMPv3 notifications and/or informs. This additional information comes fromthe usmUser records in /boot/net-snmp/snmp.conf. A usmUser record is a space delimited record on
one line with the following fields:

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Field#
1
2
3
4
5
6
7
8
9
10
11
12

Field Name
usmUser
usmStatus
userStorageTypeengineIDname
secNamecloneFrom
authProtocol
authKey
privProtocol
privKey
userPublicString

Field Value
usmUser[a number (most likely 1)][a number (most likely 3)][0x followed by a number string/hash][0x followed by a number string/hash][0x followed by a number string/hash][NULL, unless user was created from a clone][a dotted number representing: MD5, SHA, ““][0x followed by a number string/hash][a dotted number representing: DES, AES, “ “]
[0x followed by a number string/hash][0x followed by a number string/hash]snmptrap requires (depending on the level of security) the use of fields 4, 5, 8, 9, 10, and 11. Your

SNMP management station(s) will need to be configured to handle these hashed values.

Additionally, in /etc/snmptraps.conf you will need to change the setting for V3 to ON. Copy
snmptraps.conf to /boot/etc/ after you have made those changes so settings will be saved throughreboots with cp -a snmptraps.conf /boot/etc/snmptraps.conf.
You should leave V1V2C set to ON until you verify that you can receive SNMPv3 notifications/informs. Then you can change the value to OFF.

Example of usmUser Record

The image above shows an example of a usmUser record, where the fields are:Field#
5&6
8
9
10
11

Disable or
Restrict Access

Example Field Value
hashed from the value root
MD5
hashed from the value endrun_1
DES
hashed from the value endrun_1

To disable SNMP, see Chapter 5 - Security, Disable SNMP, SSH and HTTPS. To restrict access to
specific hosts see Chapter 5 - Security, Restrict Access - Telnet, SSH and SNMP.

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Chapter Seven

Network Time Protocol (NTP)
This chapter describes how to configure the Meridian II NTP Server. It also includes brief instruction
for setting up NTP Clients on your Unix-like or Windows platform. This manual is not a ‘How-To’
on installing and using NTP. Only basic approaches to NTP client configuration for operation withMeridian II will be described. If you have never used NTP, then you should spend some time reading the on-line documents, especially the Distribution Notes, FAQ and Configuration subject matter,
which are available at:
For Linux:
nwtime.org/documentationandlinks/
or for Windows:
docs.microsoft.com/en-us/windows-server/networking/windows-time-service/windows-time-service-top

A simple introduction to NTP is here:
endruntechnologies.com/pdf/NTP-Intro.pdf

Configuring the
NTP Server

Configuring the Meridian II as a Stratum 1 Server

To configure your Meridian II as a Stratum 1 NTP Server you must have successfully completed
the Basic Installation procedures in Chapter 2. By default, Meridian II is configured to respond to
NTP requests from clients that may or may not be using MD5 authentication. If the clients are using
MD5 authentication, they must be configured properly with the same MD5 authentication keys as
Meridian II. If you need to modify the factory default Meridian II MD5 keys (recommended) or set
up broadcast/multicast operation, then you will need to reconfigure the NTP subsystem. You may
perform the configuration from either a telnet or ssh session, the front-panel keypad or the local
RS-232 console.

NOTE
If you would like to configure your server for multicast operation, configure it as you would for broadcast
operation, with the exception that you must enter this specific NTP IPV4 multicast address: 224.0.1.1, or
this specific IPV6 multicast address ff05::101, when you are prompted to enter the broadcast address.

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Configuring NTP Using the Front-Panel Keypad/Display
To configure NTP using the front-panel keypad go to the Main Menu display. Press the RIGHT arrow key until the “NTP” selection is highlighted. Press ENTER again. Press the RIGHT arrow key
to highlight “Setup” and press ENTER. From this display you can configure broadcast/multicast
mode. You can also select previously configured MD5 authentication keys from this display. However, to configure new keys you will need to run ntpconfig (see below).
Configuring NTP Using the Network Interface or Serial PortThe following shows the question and answer configuration utility called ntpconfig. The userentered responses are shown in a larger font size.
Meridian II(root@Meridian II:~)-> ntpconfig**************************************************************************************************Network Time Protocol Configuration******************************************************************************************************
This script will allow you to configure the ntp.conf and ntp.keys files**
that control Meridian II NTP daemon operation.
****
You will be able to create new MD5 authentication keys which are stored**
in the ntp.keys file.
****
You will be able to update the authentication related commands in the**
ntp.conf file.
****
You will be able to configure the “broadcast” mode of operation, with**or without authentication. If you supply the multicast address instead**of your network broadcast address, then you will be able to configure**
the time-to-live of the multicast packets.
****
The changes you make now will not take effect until you re-boot the**
Meridian II. If you make a mistake, just re-run ntpconfig prior to**
re-booting.
****
You will now be prompted for the necessary set up parameters.
*****************************************************************************************************************************************************************---MD5 Keyfile Configuration

Would you like to create a new ntp.keys file? ([y]es, [n]o)y

You will be prompted for a key number (1 - 65534), then the actual key.
When you have entered all of the keys that you need, enter zero at the next
prompt for a key number.
MD5 keys may contain from 1 to 31 ASCII characters. They may not containcontain SPACE, TAB, LF, NULL, or # characters! If the key is longer than
20 characters, then only the valid hexadecimal characters(0 - 9, a, b, c, d, e, f) may be used.

Enter a key number (1-65534) or 0 to quit:

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NETWORK TIME PROTOCOL (NTP)Enter the key (1-31 ASCII characters):

EndRun_Technologies

Writing key number: 1 and Key: EndRun_Technologies to ntp.keys
Enter a key number (1-65534) or 0 to quit:
Enter the key (1-31 ASCII characters):

2

Meridian II

Writing key number: 2 and Key: Meridian II to ntp.keys
Enter a key number (1-65534) or 0 to quit:

0---NTP Authentication Configuration

Do you want authentication enabled using some or all of the keys in
the ntp.keys file? ([y]es, [n]o) y
You will be prompted for the key numbers (1 - 65534), that you want NTP to“trust”. The key numbers you enter must exist in your ntp.keys file. If you
do not want to use some of the keys in your ntp.keys file, do not enter them
here. NTP will treat those keys as “untrusted”.
Clients that use any of the “trusted” keys in their NTP polling packets will
receive authenticated replies from the Meridian II. When you have entered
all of the “trusted keys” that you need, enter zero at the next prompt for a
key number.
Enter a trusted key number (1-65534) or 0 to quit:

1Enter a trusted key number (1-65534) or 0 to quit:

2

Enter a trusted key number (1-65534) or 0 to quit:

0---NTP Broadcast/Multicast Configuration

Would you like to enable broadcast/multicast server operation? ([y]es, [n]o)y

Set the network broadcast/multicast address for the Meridian II
to use. For broadcast mode on IPV4 networks, this address isthe all 1’s address on the sub-net.
Example: 111.112.113.255
On IPV6 networks, there is more than one way todefine a range of multicast addresses:
Example: ff05::1 (all nodes on the local site)
Example: ff02::1 (all nodes on the local link)
There are specific multicast addresses assigned for NTP Operation:
For IPV4 multicast operation, it is this specific address-> 224.0.1.1
For IPV6 multicast operation, it is this specific site scope address-> ff05::101
Enter IP address for NTP broadcast/multicast operation(aaa.bbb.ccc.ddd or aaaa::bbbb ): 224.0.1.1
You have selected multicast operation. Enter the TTL value that isneeded for multicast packets on your network (1, 32, 64, 96, 128, 160, 192, 224):

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It is highly recommended that authentication be used if you are using NTP
in broadcast/multicast mode. Otherwise clients may easily be “spoofed” bya fake NTP server. You can specify an MD5 key number that the Meridian II
will use in its broadcast/multicast packets. The clients on your network must
be configured to use the same key.
Would you like to specify an MD5 key number to use withbroadcast/multicast mode? ([y]es, [n]o) yEnter the MD5 key number to use (1-65534):2***************************************************************************************************************************************************************** The Meridian II Network Time Protocol configuration has been updated.
****
Please re-boot now for the changes to take effect.
************************************************************************************************************************************************************************************************************************************************

Configuring the Meridian II as a Stratum 2 Server

Operating Meridian II as a Stratum 1 Server is the recommended mode. However, there are times
when Stratum 2 operation is a good strategy:
1. When you want a backup source of time. In this case, Meridian II will operate as a Stratum 1
Server as long as it is locked to the GPS signal. If it loses the signal, then Meridian II will start todrift away from “perfect” time. Eventually, when it has drifted 10 milliseconds, it reach the unlocked
condition and stop serving time on your network. If you have Meridian II configured for Stratum 2
operation, then it will continue serving time, using another Time Server as its reference. If Meridian
II is later able to acquire lock on the GPS signal again, it will switch back to Stratum 1 operation.
2. When you want your Meridian II to serve accurate time, but you don’t want to use the antenna(for some reason). In this case, Meridian II can operate solely as a Stratum 2 server, with no antennaconnected.
Since there are innumerable ways to configure your network with Stratum 2 servers, specific insructions for how to do that are beyond the scope of this manual. General instructions on how to edit thentp.conf file are below.
Edit ntp.conf File
You must edit the ntp.conf file in order to point your Stratum 2 server at a Stratum 1 server. Edit /etc/
ntp.conf and add your server line(s). (See Appendix C - Helpful Linux Information for information
on a simple editor.) Here is an example:
server 192.168.1.1

Or, if you have set up a domain name server via netconfig, here is another example:
server your.timeserver.com

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IMPORTANTDo not remove the server lines for the refclock. Even if your Time Server is not connected to an antenna,
the refclock server lines must remain.
Now save the edited file and copy it to the non-volatile flash partition with this command:
cp -p /etc/ntp.conf /boot/etc

Mask Alarm
In Stratum 1 operation an alarm will be indicated when there is a loss of signal or if the antenna is
not connected. For Stratum 2 operation you may not want to see these alarms. You can mask them(prevent them from showing) by using the console port (serial/network) commands setsigfltmask
and setantfltmask. Or, on the front-panel keypad/display go to the Faults submenu. Look for
SigFltMask and AntFltMask and set them appropriately.

Setting Up NTP Clients on
Unix-like Platforms

To configure your Unix-like computer to use your Meridian II, you must have successfully completed
the NTP Server basic installation procedure described above. It is expected that you are, or haveaccess to, a capable Unix/Linux system administrator and know more than a little about installing
distributions from source code. Installation must be performed by a user with root priviledges on thesystem.
If you have access to a usenet news server, many problems may be solved by the helpful people who
participate in the Internet news group devoted to NTP at comp.protocols.time.ntp.
Three methods of using Meridian II with NTP clients on Unix-like platforms will be described:
Basic: This is the simplest, and will operate without MD5 authentication. NTP beginners should
always perform this setup first.
MD5: This method is trickier only because MD5 keys must be set up and distributed accurately to
the NTP clients in a secure way. Meridian II is factory configured to authenticate its replies to NTP
MD5 clients using its default set of keys.
Broadcast/Multicast: This method simplifies configuration of the clients on large networks since
specific server addresses need not be configured in each client’s /etc/ntp.conf file. It can be configured either with or without MD5 authentication. However, it is highly recommended that authentication be configured when using broadcast/multicast mode due to the relative ease with which a fake
NTP server can take over the clock setting of the broadcast/multicast clients on the network.

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Unix-like Platforms: Basic NTP Client Setup
Basic setup is relatively simple, if:• You have been able to successfully communicate with Meridian II on your network.
• You have installed NTP on your client computer.
Configure NTP
You must edit the ntp.conf file which ntpd, the NTP daemon, looks for by default in the the /etc
directory. Add this line to the ntp.conf file:server 192.168.1.120

This line tells ntpd to use the NTP server at address 192.168.1.120 in addition to any other servers
which might also be configured in the client’s ntp.conf file.
Restart ntpd to have it begin using Meridian II. Use the NTP utility ntpq to check that ntpd is able
to communicate with Meridian II. After issuing the commandntpq

you will see the ntpq command prompt:
ntpq>

Use the commandpeers

to display the NTP peers which your computer is using. One of them should be the Meridian IIserver which you have just configured. You should verify that it is being ‘reached’. (You may haveto continue issuing the peers command for a minute or two before you will see the ‘reach’ countincrement.) If you have other peers configured, verify that the offset information for the Meridian IIserver peer and your other peers is in agreement to within a few milliseconds, assuming that the otherpeers are synchronized to that level of accuracy.
It may also be useful to start the NTP daemon in ‘debug’ mode (ntpd -d) to confirm successful configuration. Refer to the NTP documentation for detailed usage of these debug utilities.

Unix-like Platforms: MD5 Authenticated NTP Client Setup
MD5 authenticated setup is relatively simple, if:• You have been able to successfully communicate with Meridian II on your network.
• Your Meridian II has been configured to perform authentication either by factory default, or byrunning the ntpconfig shell script. The example Meridian II authentication configuration shownin Configuring NTP Using the Network Interface or Serial Port above, will be assumed in the example configuration commands shown here.
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NETWORK TIME PROTOCOL (NTP)• You have installed NTP on your client computer.
• You have successfully performed the Unix-like Platforms: Basic NTP Client Setup on your clientcomputer.
Create the ntp.keys File
You must create a file named ntp.keys in the /etc directory. It must be a copy of the one residing in
the /etc directory of your Meridian II. You can telnet into your Meridian II and start an ftp session with your client computer to send the Meridian II’s /etc/ntp.keys file to your client computer,
use the secure copy utility scp, or you can just use a text editor on your client computer to create anequivalent file.

IMPORTANT
Handling of the /etc/ntp.keys file is the weak link in the MD5 authentication scheme. It is very important that it is owned by root and not readable by anyone other than root.

After transferring the file by ftp, and placing it in the /etc directory on the client computer, issue
these two commands at the shell prompt:
chown root.root /etc/ntp.keys
chmod 600 /etc/ntp.keys

Configure NTP
You must edit the ntp.conf file which ntpd, the NTP daemon, looks for by default in the /etc directory. Assuming that you have created two trusted keys as shown in Configuring the NTP Server Using
the Network Interface or Serial Port above, add these lines to the end of the ntp.conf file:keys /etc/ntp.keys
trustedkey 1 2

Modify the line added previously in Unix-like Platforms: Basic NTP Client Setup so that authentication will be used with the Meridian II server using one of the trusted keys, in this example, key # 1:
server 192.168.1.120 key 1

Restart ntpd to have it begin using the Meridian II server with MD5 authentication. Use the NTP
utility ntpq to check that ntpd is able to communicate with Meridian II. After issuing the commandntpq

you will see the ntpq command prompt:
ntpq>

Use the command
peers

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to display the NTP peers which your computer is using. One of them should be the Meridian IIserver which you have just configured. You should verify that it is being ‘reached’. (You may haveto continue issuing the peers command for a minute or two before you will see the ‘reach’ countincrement.)
You can verify that authentication is being used by issuing the commandassociations

to display the characteristics of the client server associations. In the “auth” column of the display,
you should see “OK” for the row corresponding to the Meridian II server. If you see “bad”, you
should wait a few minutes to be sure that there is a problem since “bad” is the initial state of thissetting. If the “bad” indication persists then you must check your configuration for errors. Typically this is due to a typing error in creating the /etc/ntp.keys file on the client that causes a mismatch
between the keys being used by the server and client. (If you transfer the file by ftp or scp, thisshouldn’t be a problem.) It is also possible to have a typing error in the /etc/ntp.conf file that causes
the needed key to not be included in the “trustedkey” list.

Unix-like Platforms: Broadcast/Multicast NTP Client Setup
Broadcast/multicast client setup is relatively simple, if:• You have been able to successfully communicate with Meridian II on your network.
• Your Meridian II has been configured to perform broadcasts or multicasts by running the ntpconfig shell script. (This is not the factory default configuration, so be sure to run ntpconfig.) If
you are going to use MD5 authentication, your Meridian II must have been configured to operate withauthentication in the broadcast/multicast mode, and you must know which of the trusted keys it is using for broadcast/multicast operation. The example Meridian II configuration shown in Configuring
the NTP Server above will be assumed in the example configuration commands shown here.
• You have installed NTP on your client computer.
• You have successfully performed the Unix-like Platforms: MD5 Authenticated NTP Client Setup
on your client computer, if you plan to use MD5 authentication.
Configure NTP Client for Broadcast
You must edit the ntp.conf file which ntpd, the NTP daemon, looks for by default in the /etc directory. Assuming that your Meridian II server has been configured to use key 2 for broadcast authentication as shown in the example in Configuring the NTP Server above, make sure that key 2 is includedin the trustedkey line, and add this line to the end of the ntp.conf file:broadcastclient

If you are not using MD5 authentication, you would add these lines:
disable authbroadcastclient

You may remove the line added previously in Unix-like Platforms: Basic NTP Client Setup:
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server 192.168.1.120

or the authenticated version added in Unix-like Platforms: MD5 Authenticated NTP Client Setup:server 192.168.1.120 key 1

Configure NTP Client for Multicast
You must edit the ntp.conf file which ntpd, the NTP daemon, looks for by default in the the /etc
directory. And add these lines for multicast:multicastclient 224.0.1.1

or for IPv6:
multicastclient ff05::101

If you are not using MD5 authentication, you would add these lines:
disable authmulticastclient 224.0.1.1

or for IPv6:
disable authmulticastclient ff05::101

You may remove the line added previously in Unix-like Platforms: Basic NTP Client Setup:server 192.168.1.120

or the authenticated version added in Unix-like Platforms: MD5 Authenticated NTP Client Setup:server 192.168.1.120 key 1

Test Broadcast/Multicast
Restart ntpd to have it begin using Meridian II as a broadcast or multicast server. Use the NTP utility ntpq to check that ntpd is able to communicate with Meridian II. After issuing the commandntpq

you will see the ntpq command prompt:
ntpq>

Use the commandpeers

to display the NTP peers which your computer is using. One of them should be the Meridian IIserver which you have just configured. You should verify that it is being ‘reached’. (You may haveto continue issuing the peers command for a minute or two before you will see the ‘reach’ countincrement.)81

Meridian II User ManualCHAPTER SEVEN

If you are using authentication, you can verify that authentication is being used by issuing the commandassociations

to display the characteristics of the client server associations. In the “auth” column of the display,
you should see “OK” for the row corresponding to the Meridian II server. If you see “bad”, you
should wait a few minutes to be sure that there is a problem since “bad” is the initial state of thissetting. If the “bad” indication persists then you must check your configuration for errors. Typically this is due to a typing error in creating the /etc/ntp.keys file on the client that causes a mismatch
between the keys being used by the server and client. (If you transfer the file by ftp or scp, thisshouldn’t be a problem.) It is also possible to have a typing error in the /etc/ntp.conf file that causes
the needed key to not be included in the “trustedkey” list.

Setting Up NTP Clientson Windows

To configure your Windows computer to use your Meridian II, you must have successfully completed
the procedures in Configuring the NTP Server above. Client installation must be performed by auser with administrative priviledges.
If you have access to a usenet news server, many problems may be solved by the helpful people who
participate in the Internet news group devoted to NTP at comp.protocols.time.ntp.
The most common NTP client on Windows platforms is described below. Information on other NTP
Client software is available at:
endruntechnologies.com/products/ntp-time-servers/ntp-client-software
Windows: W32Time
Windows uses a time service called W32Time which is automatically enabled by default during
Windows installation. w32tm.exe synchronizes time in different ways, depending on the network
implementation used. When peer-to-peer networking is used, then each individual workstation synchronizes to the NTP Server. For details, copy and paste this into your browser:
docs.microsoft.com/en-us/windows-server/networking/windows-time-service/windows-time-service-tools-and-settings

However, the most common method is with Windows Domain Networking. In this case, you must
configure the Primary Domain Controller (PDC) to synchronize to the NTP Server. All other servers
and workstations in the domain synchronize to the PDC. The default Windows installation procedure
automatically configures workstations and servers to synchronize to the controlling PDC. So, only
the PDC needs to be configured to synchronize to the NTP Server.

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Security

For Unix-like platforms you can configure your NTP clients for secure MD5 authentication. See
Unix-like Platforms: MD5 Authenticated NTP Client Setup. You can also restrict NTP query access - see below.

Restrict NTP Query Access

The Network Time Protocol (NTP) implementation in Meridian II is built from the reference distribution at:
nwtime.org/downloads/
By factory default, remote control and query of the NTP daemon ntpd is disabled. Query-onlyoperation is supported only from processes running on Meridian II itself, i.e. from the localhost. This
restricts access to ntpd from remote hosts using either of the two NTP companion utilities ntpq and
ntpdc.
Control via these two utilities is disabled in the /etc/ntp.conf file in two ways. First, MD5 authentication keys are not defined for control operation via a requestkey or controlkey declaration. Second,
this default address restriction line is present in the file:
restrict default nomodify noquery nopeer
restrict 127.0.0.1 nomodify
restrict 0::1 nomodify

The first line eliminates control and query access from ALL hosts. The second and third lines disable
the localhost from making any modifications to the ntpd daemon, but query access is not affectedby this restriction. These lines must not be removed, as they are necessary for various monitoringprocesses running on Meridian II to function properly.
Knowledgable NTP users who would like to customize the security aspects of the configuration of the
NTP daemon in Meridian II should edit the /etc/ntp.conf file directly and then copy it to the /boot/etc
directory. Be sure to retain the ownership and permissions of the original file by using cp –p when
performing the copy.

CAUTION
If you are planning to make changes to the /etc/ntp.conf file, you must NOT restrict query access fromthe local host to the NTP daemon. Various system monitoring processes running on the system require thisaccess.
An example follows which shows how to allow query access from a specific remote host with IP
address 192.168.1.10 while also allowing processes running on Meridian II to have query access as
well:
restrict default noquery nomodify nopeer
restrict 127.0.0.1 nomodify
restrict 0::1 nomodify
restrict 192.168.1.10 nomodify

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"Smarter Timing Solutions"

Chapter EightIPv6 Information

The Meridian II Precision TimeBase supports IPv6 out-of-the-box with a modern version 3.2.2 Linuxkernel. During network configuration, you have the option to disable IPv6 on either or both Ethernet
ports. The IPv6 addressing scheme will see expanding deployment in the near future due to the factthat there are no longer any IPV4 addresses to be allocated in many regions of the world.

IPv6
Capabilities

The presence of an IPv6-capable kernel will automatically enable most of the IPv6 capabilities. By
default, autoconfiguration of the Ethernet interfaces via IPv6 Router Advertisements is enabled. To
disable acceptance of Router Advertisements, or to configure a static IPv6 address and default IPv6
gateway, and to configure IPv6 domain name servers, you must either run the interactive netconfig
script or use the front-panel keypad/display. Either method will allow you to configure your Ethernet
interface for both IPv4 and IPv6 operation. Using the netconfig script has the advantage that you
can also configure the hostname and domainname for the unit.

OpenSSH

By default, sshd is factory-configured to listen on both IPv4 and IPv6 addresses. It may be forced tolisten on either IPv4 only, or IPv6 only by editing the /etc/ssh/sshd_config file and modifying the AddressFamily directive, and then copying it to /boot/etc/ssh. Refer to the sshd_config man page fordetailed information (man sshd_config).

Apache HTTP

By default, httpd is factory-configured to listen on both IPv4 and IPv6 addresses. It may be forced
to listen on either IPv4 only, or IPv6 only by editing the /etc/httpd/httpd.conf configuration file andadding a Listen directive, and then copying it to /boot/etc/httpd. Refer to the Apache HTTP documentation for details.

Net-SNMP

By default, snmpd is factory-configured to listen on both IPv4 and IPv6 addresses. This may bechanged by editing /etc/rc.d/rc.snmpd and modifying the agent address argument passed to snmpd atstart-up, and then copying it to /boot/etc/rc.d.

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By default, ntpd is factory-configured to listen on both IPv4 and IPv6 addresses on all interfaces.
This may be changed by editing /etc/ntp.conf and adding the desired interface directives toachieve the desired behavior, and then copying it to /boot/etc. For example, adding this line:
interface ignore ipv6

will cause ntpd to not bind to any IPv6 addresses. Refer to the NTP documentation for details on theinterface directive.

IPv4-Only Protocols

There are several protocols running on Meridian II which are not IPv6 capable: telnet (client andserver), ftp and dhcpcd. Due to their intrinsic insecurity, telnet and ftp are rapidly being deprecated, and probably have little business running over an IPv6 network. The address autoconfiguration
capabilities of IPv6 along with the Neighbor Discovery Protocol (NDP) make the DHCP protocol lessimportant in IPv6 networks. The optional PTP/IEEE-1588 protocol is also not available on IPv6.

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Chapter Nine

Optional Precision Time Protocol (PTP/IEEE-1588)
This chapter contains the configuration and status information for the optional Precision Time Protocol. PTP version 2 is supported. The PTP protocol running on Meridian II is a full Grandmaster
Clock (default profile) implementation of the IEEE-1588-2008 standard.

Software Option

The PTP/IEEE-1588 protocol is an optional feature in the Meridian II. Read Appendix I - Software
Options if you need information on how to install a software option. To see whether this option is
installed on your Meridian II, use the installed_sw_opts command:
Command:installed_sw_opts
Meridian II reply:<no reply>
In this case, there is no PTP option installed. Contact EndRun Technologies if you would like toobtain PTP for one or both ports. In the case below, PTP is installed on both ports.
Command:installed_sw_opts
Meridian II reply:The PTP0 Daemon Option is Installed.
The PTP1 Daemon Option is Installed.

About PTP

The PTP implementation in Meridian II is based on the distribution at the PTPd website:
ptpd.sourceforge.net
For more information about the ptpd daemon and to obtain PTP Slave software, refer to the PTPd
website. When downloading PTP Slave software from the PTPd website, be sure to obtain this version: ptpd-2.2.2.tar.gz.
An excellent book which describes the PTP Master and Slave operation is:
Measurement, Control, and Communication using IEEE 1588,
John C. Eidson, Springer, November 2006.
More information on IEEE-1588 PTP can be found at the NIST National Institute of Standards andTechnology IEEE 1588 website:
nist.gov/el/isd/ieee/ieee1588.cfm

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Two Gigabit Ports

The PTP daemon status and configuration is supported from two PTP companion utilities ptpstatx
and ptpconfigx, where x is network port 0 (eth0) or 1 (eth1). The following table shows Meridian II utilities that pertain to PTP:

PTP

DaemonStatusConfiguration

ptpd0
ptpd1

ptpstat0
ptpstat1

ptpconfig0
ptpconfig1

PTP can be enabled on one or both network ports (eth0 and eth1). If PTP is enabled on only one
port, then eth0 is the network port identifier and you would use ptpstat0 and ptpconfig0 for
PTP status and configuration. If PTP is enabled on both ports, then both eth0 and eth1 will be used.

PTP Configurationand Status

If the PTP/IEEE-1588 Option is installed in your Meridian, then you can configure PTP and get status
information via the front-panel keypad./display or the command line interface. To confirm whether
this option is installed, enter the following command:orCommand:installed_sw_opts
MeridianII reply: The PTP0 Daemon Option is Installed. (PTP installed on port 0 only.)
MeridianII reply: The PTP0 Daemon Option is Installed. (PTP installed on both ports.)
The PTP1 Daemon Option is Installed.

Read Appendix I - Software Options if you need information on how to install a software option.

Default PTP Configuration Settings

The default PTP configuration settings in Meridian II are shown below. If you need to modify thesesettings then you will need to reconfigure the PTP Subsystem. Default PTP settings are:Sync Interval
Announce Inverval
Priority 1
Priority 2
Delay Mechanism
DomainPTP Time ModePTP TTL
Transmission Mode

88

Port 0 (eth0)
1 second
2 seconds
128
128
E2E
0
PTP
1
Multicast

Port 1 (eth1)
1 second
2 seconds
128
128
E2E
1
PTP
1
MulticastMeridian II User ManualPTP/IEEE-1588

PTP Configuration and Status Using the Keypad/Display

If your unit has the optional PTP capability then there will be an item in the list of Main Menu selections called: “PTP”. Press the RIGHT/LEFT arrow key until this is highlighted and press ENTER
to select it. Then press the RIGHT/LEFT arrow keys to highlight “Status” or “Setup” and press
ENTER.
The “Status” selection will let you see the current status of the PTP Subsystem.
For the “Setup” selection, press EDIT to reconfigure PTP. The sequence of edit displays will guide
you through the setup process. Press the HELP key at any time to view the context-sensitive help
information. When you are finished the unit will reset.

PTP Configuration Using the Network or Serial Port

The ptpconfig0 or ptpconfig1 command starts an interactive shell script that will allow you to
configure the PTP Subsystem of Meridian II. You will be prompted to set PTP parameters as follows:
ETH Port:
Sync Interval (Per Second):
Announce Interval (Seconds):
Priority1:
Priority2:
Delay Mechanism:
Domain:PTP Time Mode:PTP TTL:
Transmission Mode0 or 1
1, 2, 4, 8, 16, 32, 64, 128
1, 2, 4, 8, or 16
0-255
0-255
E2E or P2P
0-255
UTC or PTP
1-255
Multicast or Hybrid

One file is modified for each port. Either/etc/ptp0.conf for eth0 or /etc/ptp1.conf for eth1. These
are non-volatile files stored in the FLASH disk /boot/etc directory. You must reboot Meridian II after
running this script for the changes to take effect.
The following is a transcript of the question and answer configuration utility provided by ptpconfig0 or ptpconfig1. The user-entered parameters are shown in a larger font size:
Meridian II(root@host~)-> ptpconfig0********************************************************************************************Precision Time Protocol IEEE-1588 V2 Configuration**************************************************************************************************
This interactive utility will guide you in configuring the ptp daemon**
configuration file that controls its operation on port 0.
****
You will be able to configure the PTP sync interval, announce interval,**
priority1, priority2, delay mechanism , ptp domain, time mode and**time-to-live (TTL).
****
The changes you make now will not take effect until you re-boot.
**If you make a mistake, just re-run ptpconfig0 prior to**
re-booting.
****
You will now be prompted for the necessary set up parameters.
*
*
*

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Meridian II User ManualCHAPTER NINE**************************************************************************************************************************************************************---PTP Sync Interval Configuration
Set the PTP Sync Interval in packets per second (1, 2, 4, 8, 16, 32, 64, 128) 1---PTP announce interval Configuration
Set the PTP Announce Interval in seconds (1, 2, 4, 8, 16) 16---PTP Priority1 Configuration
Set the PTP Priority1 value (0-255) 127---PTP Priority2 Configuration
Set the PTP Priority2 value (0-255) 128---PTP Delay Mechanism E2E or P2P
Set the PTP Delay Mechanism (E2E or P2P) P2P---PTP Domain Configuration
Set the PTP Domain value (0-255) 0---PTP Time Mode Configuration
Set the PTP Time Mode (UTC or PTP) PTP---PTP TTL Configuration
Set the PTP TTL value (1-255) 1
Set the PTP Transmission Mode (Multicast or Hybrid) Multicast***************************************************************************************************************************************************************** The Precision Time Protocol IEEE-1588 V2 configuration has been updated.
****
Please re-boot now for the changes to take effect.
************************************************************************************************************************************************************************************************************************************************

Now reboot the system by issuing this command at the shell prompt:
rebootPTP Status Using the Network or Serial Port

The ptpstat0 or ptpstat1 command allows you to query the status of the PTP Subsystem. Following is the response to this command:
V

SI

AI

P1

P2

DM

DOM

MODE

TTL

CLASS

SCALE

STATE

CLKID

UTC UTCV

CA

L59

L61

TT

FT TM

Where:

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PTP OperationV

is the IEEE-1588 version 2 for the 2008 standard.

SI

is the PTP sync interval either 1, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, or 1/128 seconds.

AI

is the PTP announce interval, either 1, 2, 4, 8, or 16 seconds.

P1

is the PTP priority 1 in a range from 0 to 255.

P2

is the PTP priority 2 in a range from 0 to 255.

DM

is the PTP delay mechanism , either E2E or P2P.

DOM

is the PTP domain, in a range from 0 to 255.

MODE

is the PTP time mode, either UTC or PTP.

TTL

is the PTP multicast time-to-live in a range from 1 to 255.

CLASS

is the PTP clock class one of SYNCHRONIZED, HOLDOVER, or UNLOCKED.

SCALE

is the PTP timescale either PTP or ARB.

STATE

is the PTP port state one of MASTER, PASSIVE, LISTENING or INITIALIZING.

CLKID

is the PTP clock source either GPS or OSC.

UTC

is the PTP utc offset in seconds from TAI.

UTCV

is the PTP utc offset valid, either TRUE or FALSE.

CA

is the PTP clock accuracy one of 25ns, 100ns, 250ns, 1us, 2.5us, 10us, 25us, 100us,
250us, 1ms, 2.5ms, 10ms, or Unknown.

L59

is the PTP leap 59 second indicator, either TRUE or FALSE.

L61

is the PTP leap 61 second indicator, either TRUE or FALSE.

TT

is the PTP time traceable indicator, either TRUE or FALSE.

FTis the PTP frequency traceable indicator, either TRUE or FALSE.

TM

is the PTP transmission mode, either MULTICAST or HYBRIDThe Meridian II is configured as an IEEE-1588 Grandmaster Clock (default profile). Verify that the
network settings have been configured and tested using netconfig. Once the network has been
configured, the Meridian II will begin to transmit PTP Sync messages after it is locked.
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The PTP Sync Interval is user configured. 1, 2, 4, 8, 16, 32, 64, or 128 packets per second are transmitted as a multicast. The packets are only transmitted when the clock is fully synchronized or inholdover with a known clock accuracy.
The PTP Announce Interval is user configured. Packets are transmitted every 1, 2, 4, 8, or 16 seconds
as a multicast. The packets are only transmitted when the clock is fully synchronized or in holdoverwith a known clock accuracy.
The Delay Request Interval is not user-configurable. It is set to 32 seconds.
The PTP Priority 1 is user configured in a range from 0 to 255.
The PTP Priority 2 is user configured in a range from 0 to 255.

NOTE
If using a single Grandmaster, keep the default setting of 128 for Priority 1 and Priority 2. If using two
redundant Grandmasters, then you can configure the preferred clock by setting Priority 1 to 127 and Priority 2 to 128.

The PTP Delay Mechanism is user configured to either E2E or P2P. E2E uses the delay request-response mechanism and P2P uses the peer delay mechanism.
The PTP Domain is user configured in a range from 0 to 255.
The PTP Time Mode is user configured to either UTC or PTP. When UTC Time mode is configured
the clock transmits the UTC epoch and sets the PTP Scale to ARB. When the Time mode is PTP theclock transmits the PTP epoch (TAI) and sets the PTP Scale to PTP. See About the PTP Second and
UTC Time at the end of this chapter for more information.
The PTP Multicast TTL is user configured in a range from 1 to 255. For a local area network the TTL
should be configured to 1.
PTP Clock Class one of SYNCHRONIZED, HOLDOVER, or UNLOCKED. The Clock Class is
SYNCHRONIZED when the GPS Subsystem TFOM level is less than or equal to 4 (see Appendix A- TFOM). The Clock Class is HOLDOVER when the GPS Subsystem TFOM level is greater than 4
and less than 9. The Clock Class is UNLOCKED when the GPS Subsystem TFOM level is 9.
The PTP Timescale either PTP or ARB. When Time Mode is configured to PTP the clock transmits
the Timescale as PTP. When the Time mode is UTC the clock transmits the Timescale as ARB.
The PTP Port State is one of MASTER, PASSIVE or LISTENING. The PTP Port State is selected as
MASTER by the best master clock algorithm, otherwise it is PASSIVE or LISTENING.
The PTP Clock Source is either GPS or OSC. The Clock Source is GPS if the Clock Class is Synchronized, otherwise it is OSC based on the system oscillator.
The PTP UTC Offset is the offset between TAI and UTC in units of seconds.
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The PTP UTC Offset Valid is either TRUE or FALSE. The UTC Offset Valid is TRUE if the current
UTC Offset is known to be correct, otherwise it is FALSE.
The PTP Clock Accuracy is transmitted when the time is accurate to within the the following:
25ns
100ns
250ns
1us
2.5us
10us
25us
100us
250us
1ms
2.5ms
10ms
Unknown

Clock is synchronized or in holdover, PTP clock < 25 nanoseconds
Clock is synchronized or in holdover, PTP clock < 100 nanoseconds
Clock is synchronized or in holdover, PTP clock < 250 nanoseconds
Clock is synchronized or in holdover, PTP clock < 1 microsecond
Clock is synchronized or in holdover, PTP clock < 2.5 microseconds
Clock is synchronized or in holdover, PTP clock < 10 microseconds
Clock is synchronized or in holdover, PTP clock < 25 microseconds
Clock is synchronized or in holdover, PTP clock < 100 microseconds
Clock is synchronized or in holdover, PTP clock < 250 microseconds
Clock is synchronized or in holdover, PTP clock < 1 millisecond
Clock is synchronized or in holdover, PTP clock < 2.5 milliseconds
Clock is synchronized or in holdover, PTP clock < 10 milliseconds
Clock is unsynchronized, TFOM = 9

The PTP Leap 59 second indicator is either TRUE or FALSE. The Leap 59 is TRUE if the PTP Timescale is PTP and the last minute of the current UTC day contains 59 seconds, otherwise it is FALSE.
The PTP Leap 61 second indicator is either TRUE or FALSE. The Leap 61 is TRUE if the PTP Timescale is PTP and the last minute of the current UTC day contains 61 seconds, otherwise it is FALSE.
The PTP Time Traceable indicator is either TRUE or FALSE. The Time Traceable is TRUE if theTime Scale is PTP and the Clock Class is Synchronized or Holdover, otherwise it is FALSE.
The PTP Frequency Traceable indicator is either TRUE or FALSE. The Frequency Traceable is
TRUE if the Time Traceable is TRUE, otherwise it is FALSE.
The PTP Transmission Mode is either Multicast or Hybrid. Multicast Mode is the default and is defined in the IEEE-1588 standard. All packets sent from the Grandmaster are Multicast. Hybrid Modeuses Multicast and Unicast. In this mode, delay response messages are sent Unicast in response to
the slave delay request. NOTE: Unicast messages are only sent when the Delay Mechanism is configured to E2E.

About the PTP Secondand UTC TimeThe PTP Time Mode selections are PTP and UTC. The IEEE-1588 standard defines the PTP epoch
beginning at 0 hours on 1 January 1970. The time measured since this epoch is designated in thestandard as PTP seconds. The PTP second is monotonic so does not include leap seconds.
Unlike PTP, the UTC second is not monotonic, that is, from time-to-time there will be leap second
insertions. The last second of a leap insertion day is 23:59:60 making the day one second longer thana normal day ending at 23:59:59.

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Meridian II User ManualCHAPTER NINEPTP Second

When the PTP Time Mode is set to PTP, the slave clocks must utilize the current leap second and leap
second pending flags (leap_59 or leap_61) to convert the PTP second to UTC.

UTC Time

When the PTP Time Mode is set to UTC, then there will be a one second jump in time when a leap
second insertion occurs. If the PTP slave does not account for this, it will also jump. Avoid this byusing PTP Time Mode.

Multiport PTP

When only one PTP option is enabled it will be configured for eth0 PTP Domain 0. If a second PTP
option is enabled then it will be configured for eth1 PTP Domain 1. This configuration will allow
PTP to run as master on both ports.
If the PTP Domain is configured as the same value for both ports (for example, PTP Domain 0 on
eth0 and PTP Domain 0 on eth1) then eth0 Port State will be master and eth1 Port State will belistening.

Disable the
PTP Protocol

The instructions below assume that the PTP Option has been installed on Port 0 (eth0) of your Meridian II. To check, see the section titled Option at the beginning of this chapter.
To disable the Precision Time Protocol on Port 0 issue the following command:
chmod -x /etc/rc.d/rc.ptpd0

Copy the rc.ptpd0 file to the non-volatile FLASH area like this:cp -p /etc/rc.d/rc.ptpd0 /boot/etc/rc.dThen:rebootOnce PTP has been disabled, the user interface will no longer show the existence of PTP.

Re-Enable PTP

To re-enable PTP on Port 0, remove the rc.ptpd0 file from the /etc/rc.d directory as shown below:
rm /boot/etc/rc.d/rc.ptpd0

Then:reboot94

Meridian II User ManualPTP/IEEE-1588

NOTE
If PTP is also installed on Port 1, then follow the instructions above using rc.ptpd1.

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Meridian II User Manual

"Smarter Timing Solutions"

Chapter Ten

Rear-Panel Inputs/Outputs (I/O)
Standard rear-panel configuration for Meridian II is a 1 PPS and AM time code output, antenna
input, two Ethernet ports, RS-232 serial port, and AC power connector. The Meridian II is available
in both a 1U chassis and 2U chassis.
Your Meridian II provides five option module slots as well as a spare BNC on the CPU module tosupport up to 23 time and frequency outputs in the 1U chassis and 36 outputs in the 2U chassis. In
addition, AC and DC power supplies are available that can be configured in a high-reliability, dualredundant configuration. The drawings below show the rear-panel of a 1U and 2U chassis. Bothshow five option modules and optional output(s) on the CPU Module.
Status and user settings for the output signals can be easily viewed and modified via the front-panel
keypad/display or the console port. Methods to do this are described in this chapter. Refer to Appendix K - Specifications for details on signals, connector types, pinouts, etc.
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Standard I/O� ��������
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Antenna JackThis TNC connector mates with the downlead cable from the external antenna.

Ethernet Ports

These two RJ-45 connectors mate with the Ethernet twisted pair cable from the network. They are labeled with the corresponding MAC address and either “ETH0” or “ETH1”. Integrated LEDs indicate
link speed (green) and activity (amber). The green LED will pulse once for a speed of 10M, twice for
100M, and three times for 1G. Both ports provide a console interface to Meridian II. See Chapter 3- Console Port Control and Status for more information.

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Meridian II User ManualCHAPTER TEN

Serial I/O PortThis DB9M connector provides the RS-232 serial I/O console interface to Meridian II. This console
allows you to initialize and maintain Meridian II. See Chapter 3 - Console Port Control and Status
for more information. See Appendix K - Specifications, Serial Port I/O for pinout.

1 PPS Output

The 1 PPS Output shown in the drawing above as “B-1 PPS” is a standard TTL output on Meridian
II. There are optional 1 PPS signals such as: 1 PPS (RS-422), and Inverted 1 PPS. The Programmable Pulse Output also has a 1 PPS and Inverted 1 PPS selection.
The pulse width is normally 1 millisecond wide when shipped from the factory but can be changed(see below). For details on the 1 PPS signal definition see Appendix K - Specifications, 1 PPS Output.
View the 1 PPS Connector
On the front-panel display traverse to the Main Menu and then to CPU_I/O. This display lists any
connector on the CPU Module that has an optional I/O signal. Connectors are identified as A, B or C.
Select the particular connector (I/O-A, I/O-B or I/O-C) to see which signal is installed.
Or, you can use this console port command:
Command:cpuio
MeridianII reply: CPU I/O B - 1 PPS OUTPUT is Installed
Current Setting = (See systemio command)

Change the 1 PPS Pulse Width
On the front-panel display traverse to the Main Menu and then to Sys_I/O. There will be a selection
for 1 PPS_Out. Select this and you will be able to choose from among these pulse widths: 20 microseconds, 1 millisecond, 100 milliseconds and 500 milliseconds.
Or, you can use these console port commands:
Command:systemio
MeridianII reply: System I/O Signal 1 PPS OUTPUT is Installed
Current Setting = 1 Milliseconds Pulse Width

Command:systemioconfig
MeridianII reply: Interactive script is started so you can change the pulse width.
The 1 PPS is a “system signal”. This means that there is one 1 PPS signal that affects the whole system. In other words, if your Meridian II has multiple 1 PPS outputs and you change the pulse width,then all 1 PPS outputs will be affected.

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REAR-PANEL I/OTime Code Output

The Time Code output shown in the drawing above as “A-AMCODE” is a standard output on Meridian
II. There are two different kinds of Time Code outputs. Either amplitude-modulated (AM) or DCShift. DC Time Code is an option and, for example, would be labeled as “C-DCCODE”.
Time Code is a “system signal”. This means that there is one Time Code signal that affects the wholesystem. In other words, if your Meridian II has multiple Time Code outputs (AM and/or DC) and youchange the Time Code format, then all Time Code outputs will be affected.
The Time Code output is normally IRIG-B122 (AM) or B002 (DC) when shipped from the factory
but can be changed (see below). For details on signal definition see Appendix K - Specifications, AM
Code Output or Appendix K - Specifications, Optional DC Code Output on CPU Module.
View the Time Code Connector
On the front-panel display traverse to the Main Menu and then to CPU_I/O. This display lists any
connector on the CPU Module that has an optional I/O signal. Connectors are identified as A, B or C.
Select the particular connector (I/O-A, I/O-B or I/O-C) to see which signal is installed.
Or, you can use this console port command:
Command:cpuio
MeridianII reply: CPU I/O A - AM TIME CODE OUTPUT is Installed
Current Setting = (See systemio command)

Change the Time Code Format
On the front-panel display traverse to the Main Menu and then to Sys_I/O. If a Time Code output isinstalled in your unit, then there will be a selection for TCodeOut. Select this and you will be able tochoose from among several different Time Code formats.
Or, you can use these console port commands to change the format:
Command:systemio
MeridianII reply: System I/O Signal TIME CODE OUTPUT is Installed
Current Setting = IRIG-B122/B002 Format

Command:systemioconfig
MeridianII reply: Interactive script is started so you can change the Time Code format.

CPU Module Options

In addition to the standard I/O described above, the CPU Module can be configured with one (1U) or
four (2U) optional outputs. Some of these optional outputs are a Programmable Pulse Output, Digital
Code Output, DDS Output, Alarm Output, various pulse rates at RS-422 levels, and a second RS-232
serial port with a Serial Time Output. See the two sample CPU Module configurations below.

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Meridian II User ManualCHAPTER TEN

CPU MODULE
EXAMPLE (1U)ONE OPTIONALOUTPUT AVAILABLEON BNC C.

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CPU MODULE
EXAMPLE (2U)
FOUR OPTIONALOUTPUTS AVAILABLEON BNC C, D, E, F.
BNC G IS RESERVED.

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Programmable Pulse Output (PPO) Option

The PPO Option provides user-selectable, on-time pulses at decade rates from 1 PPS to 10 MPPS (1,10, 100, 1k, 10k, 100k, 1M, 10 MPPS). Other selections are 1PP60S (pulse per 60 seconds, on theminute), 1PP2S (pulse per 2 seconds, on the even second), and Inverted 1 PPS (falling edge on-time).
For details on signal definition see Appendix K - Specifications, Optional Programmable Pulse Output on CPU Module.
View and Change the PPO
On the front-panel display traverse to the Main Menu and then to CPU_I/O. This display lists any
connector on the CPU Module that has an optional I/O signal. Connectors are identified as A, B or C.
Select the particular connector (I/O-A, I/O-B or I/O-C) to see which signal is installed. To change the
PPO pulse rate press EDIT.

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REAR-PANEL I/O

Or, you can use these console port commands:
Command:cpuio
MeridianII reply: PROGRAMMABLE PULSE OUTPUT is Installed
Current Setting = OFFCommand:cpuioconfig
MeridianII reply: Interactive script is started so you can change the pulse rate.
Trigger PPO Function
When the PPO option is installed on the CPU Module, then the triggerppo command is available
via the console port. (The trigger PPO function is not available on option modules.) The triggerppo is used to generate an on-time pulse via the PPO BNC. Multiple instances of this command canbe running for different pulse output times, allowing scheduling of multiple triggers.
The format of the command is:triggerppo = X hh:mm:ss<CR>
Where:
X

is the CPU I/O port of the PPO Option BNC (A,B,C,D,E or F).

hh:mm:ss is the UTC time-of-day for the trigger, with 1 second resolution.
<CR>

is the ASCII carriage return character (0x0D).

An example is shown here:
Command:triggerppo = A 13:50:00
MeridianII reply: OK

This will cause a pulse on BNC A at
UTC time-of-day 13:50:00.

Trigger PPO Specifications
Rising edge on time, aligned with the desired second.
Accuracy < 10 nanoseconds RMS to UTC(USNO) when locked.
Pulse width mimics the standard 1PPS Output pulse width (20 us, 1 ms, 100 ms, or 500 ms).
Multiple trigger times must be at least 2 seconds apart.
Other PPO specifications are in Appendix K - Specifications, Optional Programmable Pulse Output(CPU Module).

Trigger PPO Operational Details
The triggerppo monitors the system time and compares it to the trigger time passed to it via theconsole port interface. When the system time is about 1⁄2 second before the trigger time, then the
PPO is armed so that a single pulse occurs at the next second mark. When the system time is about a
1⁄2 second after the trigger time, then the PPO is disarmed. For other details, at the console port type:101

Meridian II User ManualCHAPTER TEN

help triggerppo

Direct Digital Synthesizer (DDS) Option

The DDS Option provides user-selectable pulse rates from 1 Hz to 10 MHz, programmable in 1 PPS
steps, including 1.544 MPPS or 2.048 MPPS. The selected pulse rate is phase locked to the systemoscillator and is not aligned with system time.
The DDS is a “system signal”. This means that there is one DDS signal that affects the whole system. In other words, if your Meridian II has multiple DDS outputs and you change the pulse rate,then all DDS outputs will be affected.
The pulse rate is 0 Hz when shipped from the factory but can be changed (see below). For details
on the DDS signal definition see Appendix K - Specifications, Optional Direct Digital Synthesizer(DDS) Output on CPU Module.
View the DDS Connector
On the front-panel display traverse to the Main Menu and then to CPU_I/O. This display lists any
connector on the CPU Module that has an optional I/O signal. Connectors are identified as A, B or C.
Select the particular connector (I/O-A, I/O-B or I/O-C) to see which signal is installed.
Or, you can use this console port command:
Command:cpuio
MeridianII reply: CPU I/O C - DIRECT DIGITAL SYNTHESIZER OUTPUT is Installed
Current Setting = (See systemio command)

Change the DDS Rate
On the front-panel display traverse to the Main Menu and then to Sys_I/O. If a DDS output isinstalled in your unit, then there will be a selection for DDS-Out. Select this and you will be able tochange the rate. Available pulse rates are 1 Hz to 10 MHz, in 1 PPS steps.
Or, you can use these console port commands:
Command:systemio
MeridianII reply: System I/O Signal DIRECT DIGITAL SYNTHESIZER OUTPUT Installed
Current Setting = 0 Hz

Command:systemioconfig
MeridianII reply: Interactive script is started so you can change the pulse rate.

10 MPPS Output Option

The 10 MPPS Rate Output Option provides an on-time pulse rate. For details on signal definition see
Appendix K - Specifications, Optional 10 MPPS Output on CPU Module.

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REAR-PANEL I/O

View the 10 MPPS Output Connector
On the front-panel display traverse to the Main Menu and then to CPU_I/O. This display lists any
connector on the CPU Module that has an optional I/O signal. Connectors are identified as A, B or C.
Select the particular connector (I/O-A, I/O-B or I/O-C) to see which signal is installed.
Or, you can use this console port command:
Command:cpuio
MeridianII reply: CPU I/O C - 10 MPPS OUTPUT is Installed

Alarm Output Option

The Alarm Output provides an open-collector output that indicates when the GPS Subsystem has lost
lock, or when serious hardware faults are detected. For a detailed description of the faults see Appendix G - System Faults.
Care should be taken not to directly connect this open-collector output to a voltage source. A series
current-limiting resistor of at least 1k ohms in value should be used. The pull-up voltage must notexceed 40V. The Alarm Output connector can be either a BNC or a terminal block. For more details
see Appendix K - Specifications, Optional Alarm Output on CPU Module.
View the Alarm Output Connector
On the front-panel display traverse to the Main Menu and then to CPU_I/O. This display lists any
connector on the CPU Module that has an optional I/O signal. Connectors are identified as A, B or C.
Select the particular connector (I/O-A, I/O-B or I/O-C) to see which signal is installed.
Or, you can use this console port command:
Command:cpuio
MeridianII reply: CPU I/O C - OPEN COLLECTOR ALARM OUTPUT is Installed

Serial Time Output Option

This option is provided on an RS-232 (or RS-422) serial port labeled “Serial Time”. It is an output
that provides a once-per-second sequence of ASCII characters indicating the current time. The “ontime” character starts transmitting within the first 20 microseconds of each second. The output starts
automatically on power-up. See Appendix K - Specifications, Optional Serial Time Output on CPU
Module for details.
The Serial Time is a “system signal”. This means that there is one Serial Time signal that affects thewhole system. In other words, if your Meridian II has multiple Serial Time outputs, and you change
the settings, then all Serial Time outputs will be affected.
There are several different formats for this ASCII string. The format, baud rate and parity can all bechanged via the front-panel keypad or via the console port. Baud rate selections are 57600, 19200,
9600, and 4800. Parity selections are odd, even, and none. Stop bits are always one. Format selections
are Sysplex, Truetime, EndRun, EndRunX, NENA and NMEA.

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View the Serial Time Connector
On the front-panel display traverse to the Main Menu and then to CPU_I/O. This display lists any
connector on the CPU Module that has an optional I/O signal. Connectors are identified as A, B or C.
Select I/O-A, I/O-B or I/O-C) to see which signal is installed.
Or, you can use this console port command:
Command:cpuio
MeridianII reply: CPU I/O A - SERIAL TIME OUTPUT is Installed
Current Setting = (See systemio command)

Change the Serial Time Settings
On the front-panel display traverse to the Main Menu and then to Sys_I/O. If a Serial Time output isinstalled in your unit, then there will be a selection for SerTimeOut. Select this and you will be able
to change the format, baud rate and parity.
Or, you can use these console port commands:
Command:systemio
MeridianII reply: System I/O Signal SERIAL TIME OUTPUT is Installed -Current Serial Time Output Baudrate Setting = 9600
Current Serial Time Output Format Setting = SYSPLEXCurrent Serial Time Output Parity Setting = ODDCurrent NMEA Sentence 1 Setting = NONE
Current NMEA Sentence 2 Setting = NONE
Current NMEA Sentence 3 Setting = NONE

Command:systemioconfig
MeridianII reply: Interactive script is started so you can change the Serial Time settings.
Sysplex Format“Sysplex” means SYStem comPLEX and is a term used to describe computing on clusters of computers. The Sysplex option is designed to provide time synchronization for an IBM Sysplex Timer. It
can also be used for precise time synchronization by any computers that do not use NTP and have an
available serial port connection. The time contained in this string format is always UTC time. The
following string is sent once each second:<SOH>DDD:HH:MM:SSQ<CR><LF>
<SOH>
DDD
:
HH
MM
SS
Q

104

is the ASCII Start-of-Header character (0x01)
is the day-of-year
is the colon character (0x3A)
is the hour of the dayis the minute of the houris the second of the minuteis the time quality indicator and may be either:<space>ASCII space character (0x20) which indicates locked?
ASCII question mark (0x3F) which indicatesthe unsynchronized condition
Meridian II User Manual

REAR-PANEL I/O

<CR>
<LF>

is the ASCII carriage return character (0x0D) and is the on-timecharacter, transmitted during the first millisecond of each second.
is the ASCII line feed character (0x0A)

Truetime Format
The format of the Truetime string is identical to the Sysplex format. The only difference between
the two is that the Sysplex format always uses UTC time. The time contained in the Truetime format
depends on the time mode of Meridian II. For example, if you want an output with this string format
that uses Local Time, then select the Truetime format.
EndRun Format
The time contained in this string depends on the time mode of Meridian II. For example, if you want
the time in this string to be UTC, then set the time mode of Meridian II to UTC. (You can do this byusing the front-panel keypad/display or the console port (see systimemodeconfig in Chapter 9- Console Port Control and Status). The following string is sent once each second:
T YYYY DDD HH:MM:SS zZZ m<CR><LF>
T
YYYY
DDD
:
HH
MM
SS
z
ZZ
m

<CR>
<LF>

is the Time Figure of Merit character described in Appendix A - TFOM.
This is the on-time character, transmitted during the first millisecond of each second.
is the year
is the day-of-year
is the colon character (0x3A)
is the hour of the dayis the minute of the houris the second of the minuteis the sign of the offset to UTC, + implies time is ahead of UTC.
is the magnitude of the offset to UTC in units of half-hours.
Non-zero only when the Time mode is Local.
is the Time mode character and is one of:
G = GPS
L = Local
U = UTC
is the ASCII carriage return character (0x0D)
is the ASCII line feed character (0x0A)

EndRunX (Extended) Format
The EndRunX format is identical to the EndRun format with the addition of two fields - the current leap second settings and the future leap second settings. The following string is sent once eachsecond:T YYYY DDD HH:MM:SS zZZ m CC FF<CR><LF>

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T
YYYY
DDD
:
HH
MM
SS
z
ZZ
m

CC
FF
<CR>
<LF>

is the Time Figure of Merit character described in Appendix A - TFOM.
This is the on-time character, transmitted during the first millisecond of each second.
is the year
is the day-of-year
is the colon character (0x3A)
is the hour of the dayis the minute of the houris the second of the minuteis the sign of the offset to UTC, + implies time is ahead of UTC.
is the magnitude of the offset to UTC in units of half-hours.
Non-zero only when the Time mode is Local.
is the Time mode character and is one of:
G = GPS
L = Local
U = UTC
is the current leap seconds value.
is the future leap seconds which will show a leap second pending 24 hours in advance.
is the ASCII carriage return character (0x0D)
is the ASCII line feed character (0x0A)

NENA Format
NENA is the National Emergency Number Association. This organization has adopted several ASCII
time code formats for use in PSAPs (Public Safety Answering Points) and they are specified in the
NENA PSAP Master Clock Standard, Issue 4. These ASCII time code formats are NENA Format 0(NENA0), NENA Format 1 (NENA1), and NENA Format 8 (NENA8):
NENA0<CR><LF>Q^^DDD^HH:MM:SS^dTZ=XX<CR><LF>
Q

^
DDD
:
HH
MM
SS
d
TZ=XX
<CR>
<LF>

106

is the time quality indicator and may be either:<space> ASCII space character (0x20) which indicates locked.
? ASCII question mark (0x3F) which indicates the unsynchronized condition.
is the space character (0x20).
is the day-of-year (001-366)
is the colon character (0x3A)
is the hour-of-the-day (00-23)
is the minute-of-the-hour (00-59)
is the second-of-the-minute (00-60)
is the DST indicator (S,I,D,O).
is the time zone where XX is 00 through 23
is the ASCII carriage return character (0x0D).
The first <CR> is the on-time character.
is the ASCII line feed character (0x0A).

Meridian II User Manual

REAR-PANEL I/O

NENA1<CR><LF>Q^WWW^DDMMMYY^HH:MM:SS<CR><LF>
Q

^
WWW
DD
MMM
YY
:
HH
MM
SS
<CR>
<LF>

is the time quality indicator and may be either:<space> ASCII space character (0x20) which indicates locked.
? ASCII question mark (0x3F) which indicates the unsynchronized condition.
is the space character (0x20).
is the day-of-week (MON, TUE, WED, THU, FRI, SAT
is the day-of-month (1-31)
is the month (JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC)is the two-digit year
is the colon character (0x3A)
is the hour-of-the-day (00-23)
is the minute-of-the-hour (00-59)
is the second-of-the-minute (00-60)
is the ASCII carriage return character (0x0D).
The first <CR> is the on-time character.
is the ASCII line feed character (0x0A)

NENA8<CR><LF>Q^^YYYY^DDD^HH:MM:SS^D+ZZ<CR><LF>
Q

^
YYYY
DDD
:
HH
MM
SS
d
+ZZ
<CR>
<LF>

is the time quality indicator and may be either:<space> ASCII space character (0x20) which indicates locked.
? ASCII question mark (0x3F) which indicates the unsynchronized condition.
is the space character (0x20).
is the four-digit year
is the day-of-year (001-366)
is the colon character (0x3A)
is the hour-of-the-day (00-23)
is the minute-of-the-hour (00-59)
is the second-of-the-minute (00-60)
is the DST indicator (S,I,D,O).
+ or - time zone offset relative to UTC (00-12)
is the ASCII carriage return character (0x0D).
The first <CR> is the on-time character.
is the ASCII line feed character (0x0A).

NMEA Format
The National Marine Electronics Association (NMEA) has developed a specification that defines theinterface between various pieces of marine electronic equipment. This standard defines “sentences”
that contain GPS position, navigation, time, and other information. Sentences that have been implemented in Meridian II conform to NMEA-0183 Specification Version 3.01 and are GGA, GLL, GSA,
RMC, VTG and ZDA. Your Meridian II can output one, two, or three of these sentences per second.

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Up to 3 sentences may be transmitted per second. The first character (“$”) of the first sentence is
the “on-time” character. Once the unit is locked to GPS, the “on-time” character starts transmitting
within the first 20 microseconds of each second as shown here:

If Meridian II is tracking more than 3 satellites, then fixes occur every 3 seconds. Therefore, thecontent of the once/second NMEA sentences will repeat 3 times.
If tracking 3 or less satellites then there are no valid fixes. Therefore, the sentences will be blank(except for the ZDA sentence):$GPGLL,,,,,,V,N*64$GPRMC,,V,,,,,,,,,,N*53
GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPGGA,,,,,,0,00,,,M,,,,*2B
GPVTG,,T,,,,N,,K,N*61$GPZDA,194530.00,22,03,2019,-6,00*7E
Not all information defined in the NMEA sentences is available from the GPS Receiver resident in
Meridian II. Following are the definitions for the NMEA sentences as implemented in this product:

GGA (GPS Fix Data)

The GGA sentence contains the time, position, and fix related data. (EndRun does not calculate meansea level.) Examples are below:$GPGGA,,,,,,,0,00,,,M,,,*2B<CR><LF>$GPGGA,173423.00,3827.030,N,12244.020,W,1,08,1.2,14.5,M,,,,0000*72<CR><LF>
Msg ID
Field 1
Field 2
Field 3108

$GPGGA
173423.00
3827.030
N

UTC time of fix (hhmmss.ss)
Latitude in ddmm.mmm
Direction of latitude (N=north, S=south)
Meridian II User Manual

REAR-PANEL I/O

Field 412244.020
Field 5W
Field 61
Field 708
Field 8
1.2
Field 914.5
Field 10 M
Field 11
empty field
Field 12 empty field
Field 13 empty field
Field 14 empty field
Checksum *72
Msg End <CR><LF>

Longitude in dddmm.mmm
Direction of longitude (W=west, E=east)
Fix quality indicator (0=fix not valid, 1=GPS fix)
Number of SVs in use, 00-08
HDOP (horizontal dilution of precision)
Altitude above WGS84 ellipsoid (we do not calculate mean sea level)“M” indicates altitude is in meters
Height of geoid (mean sea level)
Units of geoidal separation
Time in seconds since last DGPS update
DGPS station ID number

GLL (Position Data)

The GLL sentence identifies the position fix, time of position fix, and status. Examples are below:$GPGLL,,,,,,,V,N*64<CR><LF>$GPGLL,3827.030,N,12244.020,W,173423.00,A,A*34<CR><LF>
Msg ID$GPGLL
Field 13827.030
Field 2N
Field 312244.020
Field 4W
Field 5173423.00
Field 6A
Field 7
A
Checksum *34
Msg End <CR><LF>

Latitude in ddmm.mmm
Direction of latitude (N=north, S=south)
Longitude in dddmm.mmm
Direction of longitude (W=west, E=east)
UTC time of fix (hhmmss.ss)
A=data valid, V=data not valid
A=autonomous mode, N=data not valid

GSA (GPS DOP and Active Satellites)

The GSA sentence identifies the GPS position fix mode, the Satellite Vehicles (SVs) used for navigation, and the Dilution of Precision (DOP) values. DOP is an indication of the effect of satellite
geometry on the accuracy of the fix. An example is below:$GPGSA,A,1,,,,,,,,,,,,,,,*1E<CR><LF>$GPGSA,A,3,18,3,22,6,9,14,19,32,17,1,,,2.0,1.2,1.6*10<CR><LF>
Msg ID
Field 1
Field 2
Field 3
Field 4
Field 5
Field 6
Field 7
109

$GPGSA
A
3
18
3
22
6
9

Fixed text “A” shows auto selection of 2D or 3D fix
Fix type (1=fix not available, 2=2D fix, 3=3D fix)
PRN of SV used for fix on channel 1 (empty if no SV)
PRN of SV used for fix on channel 2 (empty if no SV)
PRN of SV used for fix on channel 3 (empty if no SV)
PRN of SV used for fix on channel 4 (empty if no SV)
PRN of SV used for fix on channel 5 (empty if no SV)
Meridian II User ManualCHAPTER TEN

Field 814
Field 919
Field 10 32
Field 1117
Field 12 1
Field 13 empty field
Field 14 empty field
Field 15 2.0
Field 16 1.1
Field 17 1.6
Checksum *10
Msg End <CR><LF>

PRN of SV used for fix on channel 6 (empty if no SV)
PRN of SV used for fix on channel 7 (empty if no SV)
PRN of SV used for fix on channel 8 (empty if no SV)
PRN of SV used for fix on channel 9 (empty if no SV)
PRN of SV used for fix on channel 10 (empty if no SV)
PRN of SV used for fix on channel 11 (empty if no SV)
PRN of SV used for fix on channel 12 (empty if no SV)
PDOP (position dilution of precision)
HDOP (horizontal dilution of precision)
VDOP (vertical dilution of precision)

RMC (Recommended Minimum Specific GPS Data)

The RMC sentence identifies the UTC time of fix, status, latitude, longitude, and date. Examples are
below:$GPRMC,,V,,,,,,,,,,N*53<CR><LF>$GPRMC,173831.00,A,3827.030,N,12244.020,W,0.08,158.14,200508,,,A*0D<CR><LF>
Msg ID$GPRMC
Field 1
173831.00
Field 2A
Field 33827.030
Field 4N
Field 512244.020
Field 6W
Field 70.08
Field 8158.14
Field 9200508Field 10 empty field
Field 11
empty field
Field 12 A
Checksum *0D
Msg End <CR><LF>

UTC time of fix (hhmmss.ss)
GPS receiver warning (A=data valid, V=data not valid)
Latitude in ddmm.mmm
Direction of latitude (N=north, S=south)
Longitude in dddmm.mmm
Direction of longitude (W=west, E=east)
Speed over ground, knots
Course made good, degrees True
Date of fix (ddmmyy)
Magnetic variation
Direction of magnetic variation
A=autonomous mode, N=data not valid

VTG (Course Over Ground and Ground Speed)

The VTG sentence identifies the actual course and speed relative to the ground. Course over ground
degrees Magnetic is not available. Examples are below:$GPVTG,,T,,,,N,,K,N*61<CR><LF>$GPVTG,158.14,T,,,0.08,N,0.14,K,A*74<CR><LF>
Msg ID
Field 1
Field 2
Field 3
110

$GPVTG
158.14T
empty field

Course over ground
Fixed text “T” shows degree True
Course over ground (not available)
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Field 4
empty field
Field 50.08
Field 6N
Field 70.14
Field 8K
Field 9A
Checksum *74
Msg End <CR><LF>

Degrees Magnetic (not available)
Speed over ground, knots
Fixed text “N” shows speed over ground is in knots
Speed over ground, km/hr
Fixed text “K” shows speed over ground is in km/hr
A=autonomous mode, N=data not valid

NOTE: Since fixes are received once every 3 seconds and the VTG sentence is output once/second it
will behave like this:$GPVTG,179.54,T,,,0.11,N,0.21,K,A*7D$GPVTG,0.00,T,,,0.00,N,0.00,K,A*70$GPVTG,0.00,T,,,0.00,N,0.00,K,A*70

ZDA (Time and Date)

The ZDA sentence identifies the time associated with the current 1 PPS pulse. Each sentence istransmitted within 500 milliseconds after the 1 PPS pulse is output and tells the time of the pulse thatjust occurred. If Meridian II is unsynchronized then this sentence will be composed of null fields.
Examples are below:$GPZDA,,,,,,*48<CR><LF>$GPZDA,175658.00,20,05,2008,07,00*69<CR><LF>
Msg ID$GPZDA
Field 1
175658.00
Field 220
Field 305
Field 42008
Field 507
Field 600
Checksum *69
Msg End <CR><LF>

111

UTC time at 1 PPS (hhmmss.ss)
Day (01 to 31)
Month (01 to 12)
Year (1980 to 2079)
Local time zone hour, offset from UTC (- for east longitude)
Local time zone minutes, offset from UTC

Meridian II User ManualCHAPTER TEN

Plug-In Module Options

Your Meridian II is supplied with five option slots that can be configured with a variety of plug-in
modules. Most of these modules can be added to Meridian II as “plug-and-play” options without
hardware or software modification. A Module Installation Guide is shown in Figure 1 at the end of
this chapter. At power-up, automatic recognition software detects the identity of any plug-in module installed and launches the corresponding software routines necessary to control and monitor theoperation of each module. Plug-in modules are described below.

NOTE
Five option slots will be displayed on the Web Interface, the front-panel display and in response to thepluginopts command for both the 1U and 2U chassis. However, in a 2U chassis, if there are dual-redundant power supplies installed, then seven option slots will be displayed. Why? Because in a 1U chassis
the dual power supplies reside in slots four and five. But in a 2U chassis, they reside in slots six and seven.

View the Plug-in Options
On the front-panel display traverse to the Main Menu and then to Opt_Cards. This display lists any
installed option modules. Serial numbers are shown for all option modules except the Power Supplies. You can also use the pluginopts command to view the information:
Command:pluginopts
MeridianII reply:
Slot 1:

2007-0011-405-NC Ultra Stab OCXO (10MHz Casc-Out) is Installed-4x 1VRMS Low Phase Noise Sine Wave Outputs
Serial Number 15085026
Port A Current Setting = 10MHz Out
Port B Current Setting = 10MHz Out
Port C Current Setting = 10MHz Out
Port D Current Setting = 10MHz Out
Slot 2:

No Option Installed --Slot 3:

No Option Installed --Slot 4:

No Option Installed --Slot 5:

No Option Installed --Change the Plug-in Options
Some outputs on the plug-in option modules can be changed. An example is a PPO Digital Output
Module where you can change each of the four BNC outputs to a different pulse rate. You can use
the front-panel keypad/display or the pluginoptsconfig command.
Command:pluginoptsconfig
MeridianII reply: Interactive script is started so you can change the pulse rate.

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Digital Output Module

The Digital Output Module is a “plug-and-play” option that adds four buffered outputs to yourMeridian II. Signal levels are either TTL (BNC connectors), RS-422 (DB9M) or RS-232 (DB9M).
Various output types are Programmable Pulse Output (PPO), Digital Time Code, Direct Digital Synthesizer (DDS), 1 PPS and 10 MPPS. Output types are described below. See Appendix K - Specifications, Optional Digital Output Module for signal details. Below is an example of a Digital Output
Module.

DIGITAL OUTPUT MODULE (WITH PPO)
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Digital Output Module - Programmable Pulse Output (PPO)The Programmable Pulse Output (PPO) adds four independently programmable “on-time” pulses atdecade rates from 1 PPS to 10 MPPS (i.e. 1, 10, 100, 1k, 10k, 100k, 1M, 10M PPS). Other selections
are 1PP60S (pulse per 60 seconds, on the minute), 1PP2S (pulse per 2 seconds on the even second)and Inverted 1 PPS (falling edge on time - not available in 2U chassis.) All these outputs are alignedwith the system time and with the other TTL outputs in the unit (except the DDS output, if any).
This format can be changed via the front-panel display by navigating to Main Menu > Option I/O >OptCard > (see Chapter 13 - Front-Panel Keypad/Display). Or, you can program the outputs via
the network or serial port by using console command pluginoptsconfig (see Chapter 3 - Console
Port Control & Status).
Digital Output Module - Time CodeThe format of all four outputs of the Digital Time Code will be the same format as that on thestandard CPU Module AM Code connector. This format can be changed via the front-panel display
by navigating to Main Menu > Option I/O > Sys I/O > TCodeOut (see Chapter 13 - Front-Panel
Keypad/Display). Or, you can change the time code format via the network or serial port by using
console command cpuoptsconfig (see Chapter 3 - Console Port Control & Status). When you
change the time code format selection, it affects ALL time code outputs in Meridian II.
Digital Output Module - Direct Digital Synthesizer (DDS)
Programmable synthesized pulse rates from 1 PPS to 10 MPPS in 1 PPS steps are available, including 1.544 MPPS or 2.048 MPPS. The rate output is phase locked to the system oscillator. However,
it is not aligned with system time. The synthesized rate frequency can be changed via the front-panel
display by navigating to Main Menu > Option I/O > Sys I/O > DDS (see Chapter 13 - Front-Panel
Keypad/Display). Or, you can change the synthesized rate via the network or serial port by using
console command pluginoptsconfig (see Chapter 3 - Console Port Control & Status). When

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you change the rate selection, it affects ALL DDS outputs in Meridian II. (This module may not befield-installable, depending on whether your Meridian already has a DDS installed.)

Digital Output Module - 1 PPS or 10 MPPS
This module provides four copies of either a 1 PPS or a 10 MPPS on-time rate output. This pulse rateis specified by the customer when the order is placed, preset at the factory, and cannot be changed.

Analog Time Code Output Module

The Analog Time Code Output Module is a “plug-and-play” option that adds four additional timecode outputs to your Meridian II. These buffered outputs can provide synchronization of equipment
such as synchronized generators, digital fault recorders, SCADA systems, and time displays, and aresuitable for recording onto magnetic tape or for transmission over another medium such as coaxial
cable. Available time code formats are: IRIG-B120 (IEEE-1344), IRIG-B122, IRIG-B123, NASA36, or 2137.
All four output connectors use the same code format. The format is identical to that of the Receiver/
CPU Module AM Code output which is set via console command systemioconfig (Chapter 3- Console Port Control & Status). For signal definition see Appendix K - Specifications, Optional
Analog Time Code Output Module.

ANALOG TIME CODE OUTPUT MODULE
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Low Phase Noise (LPN) Module

Meridian II can be configured with several high-performance, disciplined, 10-MHz oscillators. The
low-phase-noise outputs work in conjunction with these oscillators to provide individually buffered,spectrally pure, sine wave outputs. The levels of the contributors to spectral impurity have been
carefully controlled by the selection of the optional oscillators that are offered, and by the design ofthe option module and its integration into the Meridian II chassis. In addition, very good channel-tochannel isolation has been achieved.
The LPN Module adds four (1U / 2U) or six (2U) low-phase-noise frequency outputs to your Meridian II. The LPN Module with resident oscillator resides in Slot 1 and is not field-upgradeable.
However, additional LPN Modules (without an oscillator) can be installed in the field as plug-andplay options.

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The rear-panel outputs are labeled with their configured frequency. These frequencies are notchangeable but can be viewed via the front-panel display by navigating to Main Menu > Option I/O> OptCardx (where x = 1-5). You can also view the Low Phase Noise output configuration via the
network or serial ports by using console command pluginopts (see Chapter 3 - Console Port Control & Status). For signal definition see Appendix K - Specifications, Optional Low Phase Noise
Module.

LPN MODULE (WITH OSCILLATOR AND 5 &10 MHz)�����������

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Sine Wave Module

The Sine Wave Module is an option that adds four (1U / 2U) or six (2U) frequency outputs to yourMeridian II. This module is intended for those wanting sine wave outputs without the need for thehigh-performance low-phase-noise.
Up to five of these modules can be installed. The first one (with an oscillator) needs to be installed
and configured at the factory. Additional modules can be installed in the field as “plug-and-play” options. Available frequencies are 1 MHz, 5 MHz and 10 MHz. The rear-panel outputs are labeled with
their configured frequency. These frequencies are not changeable but can be viewed via the frontpanel display by navigating to Main Menu > Option I/O > OptCardx (where x = 1-5). You can also
view the Sine Wave Output configuration via the network or serial ports by using console command
pluginopts (see Chapter 3). For signal definition see Appendix K - Specifications, Optional Sine
Wave Module.

SINE WAVE MODULE (WITH OSCILLATOR AND 10 MHz)������������

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115������������

Meridian II User ManualCHAPTER TEN

Direct Digital Synthesizer (DDS) Sine Wave Module

The DDS Sine Wave Module is an option that adds four frequency outputs to your Meridian II. This
module produces a sine wave that is generated from the system DDS. Programmable synthesized
frequencies from 1 Hz to 10 MHz in 1 Hz steps are available, including 1.544 Hz or 2.048 Hz. The
selected frequency is phase locked to the system oscillator and is not aligned with system time. The
synthesized frequency can be changed via the front-panel display by navigating to Main Menu >Option I/O > Sys I/O > DDS (see Chapter 13 - Front-Panel Keypad/Display). Or, you can change
the synthesized frequency via the network or serial port by using console command systemioconfig (see Chapter 3 - Console Port Control & Status). When you change the selection, it affects all
DDS outputs in Meridian II. For signal definition see Appendix K - Specifications, Optional DDS
Sine Wave Module. (This module may not be field-installable, depending on whether your Meridianalready has a DDS installed.)

DDS SINE WAVE MODULE
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Telecom Clock Module

The Telecom Clock Module is a “plug-and-play” option that adds two or three outputs to your Meridian II. Two outputs are available for any combination of T1, J1, E1 and Composite Clock. An alarm
relay output is also available as an additional option. When Meridian II is configured with any of theavailable oscillator upgrades, it can operate as a Primary Reference Clock, providing high-stability
Building Integrated Timing Supply (BITS) clock signals directly to digital equipment. For signal
definition see Appendix K - Specifications, Optional Telecom Clock Module.

SAFETY WARNING
This option does not incorporate over-voltage protection suitable for connection to the public telecommunications network. Do not connect to any wiring that leaves the building.

The rear-panel outputs are labeled with their configuration (E1, T1, J1, 64kCC, Alarm). Examples
are below. This configuration cannot be changed but can be viewed via the front-panel display bynavigating to Main Menu > Option I/O > OptCardx (where x = 1-5). You can also view the Telecom
Clock Output configuration via the network or serial ports by using console command pluginopts,

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TELECOM CLOCK MODULE

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User Settings
There are user settings associated with the T1, J1, E1 and Composite Clock outputs. There are nouser settings for the optional Alarm Output. User settings are:T1/J1:
Framing Mode, Alarm Mode, Line Build-Out
E1:
Framing Mode, Alarm Mode
Composite Clock: Line Code, Alarm Mode
You can view or change the user settings for each output by using the front-panel keypad/display (seeChapter 13 - Front-Panel Kaypad and Display) or by using the console commands pluginopts
and pluginoptsconfig (see Chapter 3 - Control and Status Commands). Available selections foreach user setting are:
T1 Framing Mode:
Unframed, SF (D4) and ESF (CRC6)
T1 Alarm Mode:
N/A*, None, AIS, SSM
T1 Line Build-Out:
1-133 feet, 133-266 feet, 266-399 feet, 399-533 feet, 533-655 feet
J1 Framing Mode:SF(D4), ESF(CRC6)
J1 Alarm Mode:
None, AIS
J1 Line Build-Out:
0-655 feet
E1 Framing Mode:
Unframed,FAS Double-Frame, CRC4 Multi-Frame
E1 Alarm Mode:
N/A*, None, AIS, SSM
Comp Clock Line Code:AMI, AMI with 8kHz BPV, AMI with 8kHz BPV+400Hz non-BPV
Comp Clock Alarm Mode: N/A*, None, AIS*Alarm Mode not applicable when unframed (all ones).

117

Meridian II User ManualCHAPTER TEN�� ���� �������� �� ����� ������ � ���������� ������ ����������

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Meridian II User Manual

REAR-PANEL I/O

AlarmsMinor, Major and Critical Alarms are defined below. For further information on each fault refer tothe gpsstat command (FLTS field) in Chapter 3 - Control and Status Commands. In addition to
the fault types listed below, there will be a Critical Alarm if a serious hardware problem is detectedon the Telecom Module or the Receiver/CPU Module.

Fault Type

Critical

DAC Control Over-Range
No Signal Time-Out
FPGA Configuration Fault
FLASH Write Fault
GPS Comm Fault
Time Input Fault
No Polling Events
Antenna Fault
Power A Fault (option)
Power B Fault (option)
MTIE Exceeds 1 Microsecond*

Major

Minor
X

X
X
X
X
X
X
X
X
X
X

*The first 10 faults listed above are standard system faults. When the telecom board is installed, an
additional fault detection algorithm is active that compares the worst case holdover accuracy to thetelecom industry standard jitter/wander performance masks. This is the last fault listed in the table
above (MTIE Exceeds 1 Microsecond).
The following chart shows the G.823 and T1.101 jitter/wander MTIE mask levels that are pertinent
to the telecom option module. In addition, it shows the specified worst case accumulated time error,
while in holdover, for the various oscillator options that can be installed with the telecom option.
Since the one microsecond level is a good approximate level to the various masks, it is also thethreshold level that will induce an immediate fault on the telecom option alarm relays and SSM bits.
This level is factory configured and not user settable.
If Meridian II loses GPS signal lock then it will drift at a rate dependent upon the installed oscillator.
When it has drifted more than 1 microsecond the MTIE fault will be set and a Major Alarm will occur. The list below summarizes the chart data. It shows how long in holdover each oscillator will be
until it exceeds the one microsecond threshold:Medium-Stability OCXO:
High-Stability OCXO:
Ultra-Stable OCXO:
Rubidium:
Ultra-Stable Rubidium:119

1 hour3 hours
6 hours
6 hours
1 day

Meridian II User ManualCHAPTER TEN

Connectors and Cables
The Telecom Clock Output Module is available with two types of output connectors: BNC andRJ48C. The BNC connector is compatible with 75 ohm coaxial cable. The RJ48C connector is compatible with 100-133 ohm twisted pair. Pin assignments are:��� ���������� ���������
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Meridian II User Manual

REAR-PANEL I/O

The RJ48C connector is physically identical to an RJ45 connector. The RJ48C designation refers to
the interconnection and pairing within the applicable cable, which is different than that of Ethernet
cables. The RJ48C wiring pattern is shown below:����������� ��������� ����� ����������� � ��������� �������
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Connection to RJ48C BITS Clock Input

A crossover cable, as shown above, would be used to connect the EndRun Technologies clock buffer output on RJ48C pins 4 and 5 to equipment with the BITS clock input on RJ48C pins 1 and 2.
Equipment with the BITS clock input on pins 4 and 5 would require a straight-through cable. The
shield ground is connected on pins 7 and 8.
Connection to Wire-Wrap Terminal BITS Clock Input

Use a RJ48C cable with 22 AWG solid wire for connection to wire-wrap terminals. Either connector
can be cut off to expose the individual twisted-pairs for this application. Determine the color-codingof the twisted-pair connected to pins 4 and 5 of the remaining RJ48C connector. The wire connected to pin 4 connects to the BITS clock Ring input wire-wrap terminal and the wire connected topin 5 connects to the BITS clock Tip input wire-wrap terminal. The drain wire associated with thatshielded twisted pair connects to the GROUND terminal.
Shield Ground Connection

The shield ground should be connected to minimize cross-talk. Connection to BITS clock inputs conforming to the pin-out described in Table 1 or connection as described for wire-wrap inputs will resultin a grounded shield. However, some RJ48C BITS clock inputs are wired with the shield connections
on pins 3 and 6. This situation can be accommodated by modification or replacement the EndRunsupplied cable. This is compatible with the EndRun Technologies RJ48C clock output connector inwhich pins 4 and 5 provide the BITS clock signal, while pins 1, 2, 3, 6, 7, and 8 are not connected.
Cable (655 ft maximum)

A 10 ft. T1 crossover cable, manufactured by Stonewall Cable (P/N SC-9598-X) is a good cable for
initial testing and typical T1, E1, or 64kCC installations. For other lengths or connector configurations, use equivalent T1 or E1 cable qualified to match clock-type. T1 cable is compatible with E1
signals for short runs. Over 10 ft. use cable specified to match the application. Either cable type canbe used for 64kCC signals.

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Meridian II User ManualCHAPTER TEN

5071A Cesium Control Module

The 5071A Cesium Control Module allows you to discipline the frequency of a 5071A Primary
Frequency Standard to either the UTC(USNO) or GPS timescale via the Meridian II GPS Timebase.
(To view or change the timescale, see Chapter 3 - Control and Status Commands, systimemode andsystimemodeconfig.) In so doing, you can realize the extraordinary short to medium-term stability of
the 5071A while also maintaining strict, long term adherence to the selected timescale. The disciplining algorithm is optimized to preserve the stability of the 5071A for observation intervals less thanthe Allan deviation crossover point. This crossover point is the observation interval at which the
Meridian II GPS receiver accuracy and stability become superior to the 5071A relative to the selected
timescale. Past the crossover point, the 5071A is disciplined with a 3rd order phaselock algorithm
to agree with the Meridian II’s idea of UTC(USNO) or GPS time. Before the crossover point, the5071A is essentially free-running, as its stability is superior to that of the Meridian II.
This module resides in Slots 1 and 2. It is not field-upgradeable. The rear-panel outputs are labeledwith their configured frequency which may be a combination of 1, 5 or 10 MHz sine waves, allderived from the 5071A 10 MHz signal. These frequencies are not changeable but can be viewed via
the front-panel display by navigating to Main Menu > Option I/O > OptCard1. You can also viewthe Low Phase Noise output configuration via the network or serial ports by using console command
pluginopts (see Chapter 3 - Console Port Control & Status). For signal definition see Appendix
K - Specifications, Optional 5071A Cesium Control Module.

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The module’s DB9M connector and provided cable allow the RS-232 serial port of the 5071A to beconnected to the Meridian II for bi-directional data communication. The module’s BNC input connector and coaxial cable allow the 10 MHz output signal from Port 1 on the 5071A to be connected to
the Meridian II. The 5071A 10 MHz signal then becomes the reference for all frequency and timing
signals within the Meridian II, in the same way that the other optional oscillators (OCXO, Rubidium,etc.) operate.
The Meridian II sends commands to the 5071A to steer its frequency, monitor its health and set the
time-of-day clock on its front panel. The 5071A Operation Status and Questionable Data registers
are monitored to determine the overall functional state of the 5071A, and critical 5071A internal
diagnostic parameters are also monitored. All of this information is reported via the various Meridian II user interfaces: CLI, SNMP, HTTP and (except for the Tycho II) the front panel display. All
cesium atomic frequency standards have definite wear-out mechanisms, so monitoring these criticalparameters is recommended, as they can give some advance notice of an impending cesium beamtube failure.

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Theory of Operation
The 5071A Primary Frequency Standard is the “gold” standard of commercial Cesium frequency
standards. Their release in the early 1990’s introduced a quantum leap in performance over previous
devices, which is to this day unsurpassed. As such, they are the dominant contributors to the global
ensemble of clocks that make up the UTC time scale. International timing laboratories equipped withexotic reference frequency standards and capable of measuring the characteristics of the 5071A haveverified their performance and published their results, so they are well known.
As with all free-running clocks, they do not maintain perfect synchronization with another independent timescale, such as UTC(USNO). Error in initial frequency calibration along with the random, divergent effect of flicker frequency modulation inevitably results in the phase drifting awayfrom UTC. In order to maintain long term synchronization with the UTC(USNO) timescale, the5071A must be steered. The obvious way to do this is to measure the phase of the 5071A versus
UTC(USNO) via GPS and adjust the frequency of the 5071A based on the measurements. (In thisrespect, the 5071A is no different than the other optional oscillators which might be installed inside
the chassis of the Meridian II.)
The GPS receiver module inside of the Meridian II has the ability to phaselock its internal oscillator
to an external oscillator. This provides the most accurate and stable means of measuring the phaseof the 5071A versus GPS and ultimately UTC(USNO). The 5071A has the ability to be steered withvery fine resolution, about 6.3 parts in 1015. By combining these two features, a UTC(USNO) timeand frequency reference with extraordinary performance may be realized, with the excellent medium
to long term stability of the the 5071A and the longer term accuracy and stability of the UTC(USNO)
or GPS timescale. The 3rd order phase lock algorithm reduces the long term Allan deviation of
the 5071A from flicker frequency modulation to white phase modulation relative to the selected
UTC(USNO) or GPS reference.
Because the 5071A stability is so good, a poorly designed GPS timing receiver and frequency control
algorithm could easily degrade the normal performance of the 5071A. The Meridian II GPS receiver,when equipped with its optional Real Time Ionospheric Corrections (RTIC) algorithm and a precisely
determined antenna position, provides GPS timing measurement accuracy and stability that does notdegrade the stability of the 5071A while implementing a tight-enough control of the 5071A to realize
the long term accuracy of the reference timescale, either UTC(USNO) or GPS. The control loop
parameter “sweet spot” to achieve this was determined from the published measured performance ofthe 5071A along with the measured performance of the Meridian II GPS receiver equipped with the
RTIC option at NIST in May, 2016.
Installation
Setup of the 5071A for use with the 5071A Cesium Control Module is simple:
1. The 5071A should be powered on and the RS-232 serial port settings configured via the front
panel CONFIG->SERIAL menu:
Baud rate:
Data bits:
Parity:Stop bits:

123

9600
8
none
1

Meridian II User ManualCHAPTER TEN

Use the CONFIG->STORE menu to save the settings to non-volatile memory.
2. Verify that the 5071A is not in STANDBY mode. If it is, you must change it to NORMAL using
the CONFIG->MODE menu.
3. Connect the provided DB9F-to-DB9F null-modem cable between the 5071A Cesium Control Module connector labeled “Cesium Control I/O” and the 5071A DB9M connector labeled “RS-232C”.
4. Connect the provided BNC-to-Type-N coaxial cable between the Control Module connector labeled “10 MHz Sine Input” and the 5071A connector labeled “Port 1”.
5. Apply power to the Meridian II.
Operation
After the Meridian II has booted, verify that the 5071A Cesium Control Module was detected in the
I/O->OptCard1 menu item display. Then move to the Receiver->Osc_Stat menu and scroll throughthe items which appear there. The oscillator type displayed should be either Cesium or US-Cesium(if the 5071A has the Option 001 High-Performance beam tube). If you continue scrolling throughthese items, you will eventually get to a group of twelve 5071A-specific parameters:
Operation Status register (in human-readable format),
Questionable Data register (in human-readable format),Cesium Beam current,
C-Field current,
Ion Pump current,Electron-multiplier voltage,
Cesium Beam tube oven voltage,
Signal Gain percent of maximum,
1st microwave RF amplitude percent of maximum,
2nd microwave RF amplitude percent of maximum,
Reference oscillator oven voltage,
Reference oscillator control percent of maximum.
Alternatively, you may use the hp5071astat command to get this information. See on the next section called Cesium Status Using the Console Port.
At this point, the Meridian II will continuously monitor the operating status of the 5071A and willremain in the Warm-Up state until the 5071A has warmed up and is indicating NORMAL operationin the Operation status register. At this time, the Meridian II will transition to the Acquire state andremain there until satellites are tracked, at which point it will begin the normal GPS synchronizationand frequency locking process. Once Locked status has been achieved, the Meridian II will set the
time-of-day clock on the 5071A front panel to GPS time, and turn on the display. Prior to this, the5071A clock display will be blank. The GPS time on the 5071A display is only accurate to about 1⁄2
second. (For more accurate display of time-of-day, and to display UTC or Local time, use the front
panel display of the Meridian II.)
After achieving lock at its relatively short initial control loop averaging time, the Meridian II will
steadily lengthen the control loop averaging time for several weeks before it has reached its final
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value. During this settling period, the stability of the 5071A with Option 001 High Performance
beam tube may be slightly degraded as the shorter term GPS system noise may not be sufficiently
filtered. After the final control loop averaging time has been achieved, performance to full specifications is available.

Cesium Status Using the Console PortThe hp5071astat command returns the contents of the cesium oscillator status registers in a humanreadable form. Also included are parameters describing the inner workings of the oscillator. Below
is a sample response for this command:
Command:
hp5071astat
MeridianII reply: Operation Status:

NORMAL STEEREDQuestionable Data:
OK
Operating Parameters:
Cs Beam Current
0.100 uA
C-Field Current
12.169 mA
Ion Pump Current
0.0 uA
E-Multiplier Voltage
1928 VCs Oven Voltage
8.0 V
Signal Gain
14.4 % of maximum
RF Amplitude 1
35.7 % of maximum
RF Amplitude 2
34.9 % of maximum
Osc Oven Voltage-9.0 V
Osc Control+3.40 % of maximum

or, if the 5071A Cesium Control Module is not installed:
Command:
hp5071astat
MeridianII reply: HP5071A is Not Installed
Detailed help information is available as shown:
Command:help hp5071astat
MeridianII reply:
hp5071astat returns the contents of the Operation Status and Questionable
Data registers of the HP5071A Cesium oscillator in a human-readable form.
These are followed by a set of 10 other parameters describing the innerworkings of the Cesium oscillator.
The Operation Status is summarized in a 16 bit register, of which only
6 bits are used to indicate these conditions:
CALIBRATING (normal state during warmup)
STANDBY(non-operational maintenance mode)
ONBATTERY(on battery backup power)
NORMAL(normal state after warmup)
FATAL(fatal error, call factory)
STEERED(normal state after warmup, if steering is not zero)
NOTE: If none of these 6 bits are set, it is an indication of an
RS-232 communications fault with the HP5071A, and the Operation
Status will be reported as:

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RS-232_COMM_FAULTThe Questionable Data is also summarized in a 16 bit register, of which
only 3 bits are used to indicate these condition:
TIME(time-of-day clock is not set)
FREQUENCY(out-of-lock)
PHASE(spurious bursts)
Also reported are the:Cs Beam current(typical range unspecified),
C-Field current(10.0 to 14.05 mA, typical),Ion Pump current( 0.0 to 40.00 uA, typical),Electron-multiplier voltage(1000 to 2553 V, typical),Cs Oven voltage(
0 to
10 V, typical),Signal Gain percent of maximum(14.4 to 58.00 %, typical),
RF Amplitude 1 percent of maximum(
0 to
100 %, typical),
RF Amplitude 2 percent of maximum(
0 to
100 %, typical),Oscillator Oven voltage( -5 to-10 V, typical),Oscillator Control percent of maximum ( -95 to+95 %, typical)
Example response:
Operation Status:
NORMAL STEEREDQuestionable Data:
OK
Operating Parameters:
Cs Beam Current
0.100 uA
C-Field Current
12.168 mA
Ion Pump Current
0.0 uA
E-Multiplier Voltage
1890 VCs Oven Voltage
7.9 V
Signal Gain
14.4 % of maximum
RF Amplitude 1
35.8 % of maximum
RF Amplitude 2
34.8 % of maximum
Osc Oven Voltage-9.0 V
Osc Control+3.46 % of maximum

Faults
A 5071A alarm will show on the Meridian II if any of these conditions occur on the 5071A:
Operation Status - STANDBY or FATAL
Questionable Data - FREQUENCY or PHASE.
COMM_FAULT
For information on the Meridian II faults, see Appendix G - System Faults.

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REAR-PANEL I/OPower Supply Options

Your Meridian II can be configured with several optional power supply inputs which are listed inAppendix K - Specifications, Optional DC Power Inputs. Dual-redundant power supplies are alsoavailable.

DC Power Input

The DC power input uses a a 3-position terminal block and replaces the standard AC power input
jack.

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�Connecting the DC Power
Connect the safety ground terminal to earth ground. Connect the “+” terminal to the positive outputof the DC power source. Connect the “-” terminal to the negative output of the DC power source.
Note that Meridian II has a “floating” internal power supply, therefore either the positive or negative
output of the DC power source can be referenced to earth ground. This unit will not operate if the +/connections are reversed; however it will not be damaged by a reverse connection.

SHOCK/ENERGY HAZARD
Install in Restricted Access Location.
Use 10-14 AWG copper wire only.
Terminal block screw torque: 9 lb-in (1 n•M).
Branch circuit must have circuit breaker, 15A or less.
Power must be sourced via two pole disconnect device.
Install terminal block cover after wiring.
Dual-Redundant Power Supplies

Any combination of Universal AC and/or DC supplies is available. Primary and secondary power
supplies are connected in a dual-redundant configuration with hitless automatic primary-to-secondaryand secondary-to-primary switchover.

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Meridian II User ManualCHAPTER TEN

A fault detector monitors the status of each redundant power supply. When a fault is detected it will
trigger a system alarm. When Meridian II is configured with Dual Power Supplies, an alarm willshow if the primary or secondary supply does not have power connected.
NOTE: In the 1U chassis a dual power supply will occupy option slots four and five. In the 2U chassis a dual power supply will occupy slots six and seven.
Masking Dual Power Supply Fault Alarms
You can mask the Primary and Secondary Faults to prevent them from causing a system alarm.
Masking a fault will prevent it from causing the Alarm LED and Alarm Output (if any) from going
active. Masking a fault will NOT prevent it from showing on the front-panel System Faults display
or in the gpsstat command.
To mask the fault, traverse to the Faults Menu, then select PwrFltMask. Or, you can use the consolecommands pwrfltmask and setpwrfltmask. Parameters are either Masked or Enabled. Setting
this command to Masked will prevent a power supply fault from creating an alarm condition. The
factory default setting is Enabled.
Command:pwrfltmask
MeridianII reply: Primary Power Input Fault Alarm is MASKED
Secondary Power Input Fault Alarm is ENABLED

Command:setpwrfltmask MASKED MASKED
MeridianII reply: Primary Power Input Fault Alarm Mask set to MASKED
Secondary Power Input Fault Alarm Mask set to MASKED

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REAR-PANEL I/O"Smarter Timing Solutions"

Module Installation Guide

Meridian II Precision TimeBase / Tycho II Precision TimeBase
This is the option module installation guide for Meridian II and Tycho II. Option modules are installed in slots 1 through 5. Referring to
Figure 1 below, the CPU Module is left-most. Next is option slot 1, shown with four BNCs. Slots 2 and 3 are shown with single-slot filler
panels, while slots 4 and 5 have a double-slot filler panel installed. Option modules are not hot-swappable, but most are plug-and-play.
NOTE: Oscillator Modules must remain in the factory-installed location (slot 1 or, for rubidium, slot 1 and 2). The dual-redundant power supply (if any) is installed in slots
4 and 5. All options except the oscillators and power supplies are field-installable.

Handle option modules by the aluminum carrier only! Any contact with printed circuit board or electronic components can cause permanent damage due to static discharge. Prior to installation, touch enclosure
while holding module to equalize any static charge build-up.

STEP 1

Disconnect power and remove unit from equipment rack. Remove upper and lower screws from filler panel as shown in Figure 1. Remove filler panel by pulling it straight back. Most
option modules can be installed in any available slot. The exceptions are Oscillator, Low-Phase-Noise (see note below), and Sine Wave (see note below) Modules.
NOTE: A Low Phase Noise (LPN) or Sine Wave Module is connected directly to the adjacent module via a short jumper cable. Therefore, it must be installed next to the Oscillator Module ornext to the highest-numbered-slot LPN/Sine Module. Due to the jumper cables, all previously installed LPN Buffer Modules and/or the Oscillator Module must be removed simultaneously inorder to install a new LPN/Sine Module.
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Figure 1. Rear View Prior to Module Installation

STEP 2
Slide option module into slot as shown in Figure 2. Keep module level and in full contact with the bottom of the enclosure while sliding it straight back into the slot. With
module laying flat on bottom of enclosure, firmly press it in to seat the connector.
NOTE: For an LPN or Sine Module, use supplied cable to connect J3 (CASCADE OUT) in lower-numbered slot to J5 (CASCADE IN) in higher-numbered slot prior to simultaneously installing the interconnected modules.
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Figure 2. Side View During Module Installation

STEP 3Re-install top and bottom screws as shown in Figure 3.

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Figure 3. Rear View After Module Installation

F I G U R E 1 - PLUG-IN MODULE INSTALLATION GUIDE129

EndRun Technologies LLC
2270 Northpoint Parkway, Santa Rosa, California 95407 USA 707-573-8633
Form 5050-0026-000
August 2015

Meridian II User ManualCHAPTER TENThis page intentionally left blank.

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"Smarter Timing Solutions"

Chapter Eleven

Real-Time Ionospheric Corrections (RTIC) Option
This chapter describes the RTIC Option, its operation, and the time and frequency performance benefits to Meridian II.

Software Option

RTIC is a software option in the Meridian II. Read Appendix I - Software Options if you need information on how to install a software option. If you are unsure whether your device has RTIC installed,
use the installed_sw_opts command:orCommand:installed_sw_opts
Meridian II reply:<no reply>
Command:installed_sw_opts
Meridian II reply:The Real-Time Iono Corrections Option is Installed.

If you would like RTIC and it is not installed, then contact EndRun Technologies.

About RTIC

The Real-Time Ionospheric Corrections (RTIC) option for the Meridian II Precision TimeBase optimizes time and frequency stability and accuracy. The RTIC option uses proprietary algorithms within
EndRun’s L1 GPS timing receiver to directly measure and remove ionospheric delays in real-time.
This unprecedented real-time capability was previously only available with expensive dual frequency
L1/L2 GPS receivers.

Ionospheric Delay and Impact To GPS Time-Transfer

The largest contributor to GPS time-transfer error is the variable delay of the satellite signals as they
pass through the ionosphere, a layer of ionized particles a few hundred kilometers above the Earth’s
surface. The ionization is caused by solar radiation phenomena, and is maximum a little after local
noon and minimum a little after local midnight. The GPS signal delay through the ionosphere is
proportional to the ionization level, expressed as Total Electron Content (TEC). Data transmitted
from the satellites contain a model (Klobuchar) that receivers may use to partially compensate for this
delay. This model, however, provides only a coarse compensation for night-to-day variations in theionosphere. It is unable to compensate for the much shorter-term variations in the ionospheric delaycaused by various types of solar “storms”, and it cannot keep up with the day-to-day variations. As
such it was never intended to achieve more than about a 50% improvement over not compensating
for the ionospheric delay at all.

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Meridian II User ManualCHAPTER ELEVEN

Our Proprietary Solution

The GPS code modulation and carrier phase delays are affected differently as they propagate throughthe ionosphere. By recognizing a few other aspects of this behavior, EndRun developed the RTIC
algorithm to directly quantify the delay through the ionosphere, and resolve the code phase and carrier phase bias. The bias information enables real-time measured delay compensation in EndRun’s
proprietary, single-frequency, L1 GPS receiver. To our knowledge, this capability is unique to EndRun Technologies.
The algorithm is effective when the receiver is operating at a stationary location with continuous
tracking of at least one satellite at all times. After a 24-hour initialization period it begins producing
real-time ionospheric delay measurements, with full accuracy of those measurements achieved after
several days. When ionospheric conditions are quiet or relatively normal, this option improves theaccuracy and stability of the timing outputs by as much as a factor of three at observation intervals
between 3,000 and 100,000 seconds. During a major ionospheric storm event, the improvement
may be much greater. It is very difficult to achieve this stability over these observation intervals byanother method, as only a high-performance cesium frequency standard is stable enough to act as afilter for the timing errors caused by the GPS broadcast model. The following phase plot shows the
Meridian II with the RTIC option active (blue) compared to what the Meridian II performance would
have been using the GPS broadcast model (red). Throughout the 10-day test period the RTIC option
demonstrated substantial improvement to frequency and time-domain stability through real-time
ionospheric delay measurements and compensation.

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Performance Verified at National Institute of Standards and Technology (NIST)To characterize the performance gain of the RTIC Option, a Meridian II was sent to NIST in May of2016, where its 1PPS output was monitored continuously relative to UTC(NIST) for over 30 days.
The RTIC Option was active in the Meridian II during this time. The ionospheric delay corrections
calculated using the broadcast ionospheric model, along with the real-time corrections computed
using the RTIC Option, were logged. With these logs, the NIST timing measurements were post-processed to determine what the performance would have been if the RTIC Option had not been active,
and the broadcast model had instead been used.
The following chart shows the difference in stability between the two delay compensation methods ofthe Meridian II, along with the stability of the two performance levels of HP 5071 Cesium standards
for comparison. The Meridian II stability performance with the RTIC option exceeds the standard HP
5071 Cesium at all measurement intervals and exceeds the High Performance HP 5071 after 300,000
seconds.

RTIC Configurationand Status

If the RTIC Option is installed in your unit, then you can configure (turn on or off) and get status information via the front-panel keypad/display or the command line interface. To confirm whether thisoption is installed from the command line issue the following command:
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Command:installed_sw_opts
Meridian II reply:The Real-Time Iono Corrections Option is Installed.
(If the option is installed.)
If you need information on how to install the RTIC option, refer to Appendix I - Software Options.

RTIC Configuration and Status Using the Keypad/Display

If your unit has the optional RTIC capability then there will be an item in the list of Receiver selections called: “RTIC”. Press the RIGHT/LEFT arrow key until this is highlighted and press ENTER
to select it. Then press the RIGHT/LEFT arrow keys to highlight “Status” or “Setup” and press
ENTER.
The “Status” selection will let you see the current status of the RTIC.
The “Setup” selection lets you turn RTIC on or off.

RTIC Configuration and Status Using the Network or Serial PortThe commands listed below allow you to get the current RTIC status and turn RTIC on or off.
ionostat
This command shows parameters associated with the RTIC Option. The string contains several parameters in the format shown below:
YYYYMMDD.HH:MM:SS K.KKKe-KK V +S.SSSe-SS
where:YYYYMMDD.HH:MM:SS is the timestamp of the data.
K.KKKe-KK is the standard broadcast Klobuchar model ensemble ionospheric delay in seconds.
V is the validity of the Real-Time ionospheric delay calculations, T(rue) or F(alse).
+S.SSSe-SS is the Real-Time ensemble ionospheric delay calculation in seconds.
Here is an example:
Command:ionostat
MeridianII reply: 20160916.18:13:10 1.093e-08 F +1.093e-08
rticmodeThis command shows the operating state of the Real-Time Ionospheric Correction Option. It is either
OFF or ON. When ON, Real-Time ionospheric delays are calculated and used to compensate for the
GPS signal delay through the ionosphere. When OFF, the Real-Time delays continue to be calculated
but the standard broadcast Klobuchar ionospheric model delays are used to compensate for the GPS
signal delay through the ionosphere.
Command:rticmode
MeridianII reply: ON

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setrticmode
This command allows the root user to manually set the Real-Time Ionospheric Correction Option
mode to either OFF or ON. For the highest accuracy and stability at a static location with goodsatellite visibility, this should be set to ON. Even if this setting is ON, it will be ignored if the GPS
Dynamic mode is also ON, and real-time ionospheric delays will not be calculated. Factory default
mode is ON.
NOTE: The Real-Time Ionospheric Correction Option requires a minimum of 24 hours of operation
after lock to GPS to begin producing enhanced accuracy ionospheric delay calculations, and thesewill reach their full accuracy after several days.
It accepts one command line argument: either ON or OFF. Use the rticmode command to confirm
any change in setting.
Command:setrticmode ON
MeridianII reply: Real-Time Ionospheric Corrections Mode is ON

RTIC Performance Plots Using the HTTP Interface

Plots showing the Ensemble Ionosphere Delays are available on the Plots Page as shown below:

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RTIC Stability
Specifications

The specifications below supercede the 1PPS Stability specification and the System Oscillator Stability Table shown in Appendix K - Specifications.
1PPS Stability (RTIC Option): TDEV < 2 ns @ τ < 105 seconds, σy(τ) < 4.0x10-14 @ τ=105 secs.
System Oscillator Stability (Allan Deviation) Table:
Tau in Seconds
1
10
100
1000
10000
100000

TCXO
2.0x10-10
2.0x10-10
8.0x10-11
8.0x10-12
6.0x10-13
4.0x10-14

MS-OCXO
3.0x10-12
3.9x10-12
3.0x10-12
2.0x10-12
2.0x10-13
4.0x10-14

HS-OCXO
1.0x10-12
1.3x10-12
1.7x10-12
1.3x10-12
2.0x10-13
4.0x10-14

Tau in Seconds
1
10
100
1000
10000
1000001000000

US-Rb*
1.5x10-11
5.0x10-12
1.4x10-12
6.0x10-13
2.0x10-13
4.0x10-14

Cs**
1.2x10-11
8.5x10-12
2.7x10-12
8.5x10-13
2.7x10-13
8.5x10-14
1.0x10-14

HP-Cs**
5.0x10-12
3.5x10-12
8.5x10-13
2.7x10-13
8.5x10-14
2.7x10-14
1.0x10-14

*
**

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US-OCXO
4.0x10-13
4.5x10-13
8.5x10-13
7.0x10-13
2.0x10-13
4.0x10-14

US-Rb is only an option in the 2U version of Meridian II.
5071A Cesium Control Module is only specified with the RTIC Option.

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Chapter Twelve

Optional Synchronous Ethernet (SyncE)When locked to GPS, the Meridian II can operate as a Synchronous Ethernet Primary Reference
Clock (PRC). This chapter contains the information for the optional Synchronous Ethernet protocol(SyncE). SyncE is most often used in telecom applications.

Software Option

The Synchronous Ethernet protocol is an optional feature in the Meridian II. Read Appendix I - Software Options if you need information on how to install a software option. If you are unsure whether
your device has SyncE installed, use the installed_sw_opts command:orCommand:installed_sw_opts
Meridian II reply:<no reply>
Command:installed_sw_opts
Meridian II reply:The SYNCE0 Daemon Option is Installed.
The SYNCE1 Daemon Option is Installed.

If you would like SyncE and it is not installed, then contact EndRun Technologies.

About SyncE

Synchronous Ethernet, also referred as SyncE, is an ITU-T standard for computer networking thatfacilitates the transference of clock signals over the Ethernet physical layer (Layer 1). In addition to
the physical clock signals, the Synchronization Status Messaging (SSM) is transmitted on the datalink layer (Layer 2). The Ethernet Synchronization Messaging Channel (ESMC) contains the clock
Quality Level (QL) with the embedded SSM code.
The Meridian II is configured as a Synchronous Ethernet Primary Reference Clock (PRS) whentightly locked to GPS (TFOM <= 4. See Appendix A - TFOM). There is no SyncE user configuration
required.
Synchronous Ethernet is defined in the ITU-T:
G.8261 Architecture and wander performance
G.8262 Timing characteristics
G.8264 Ethernet Synchronization Message Channel (ESMC)
More information on SyncE can be found at the ITU-T Telecommunications Standardization Sector
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itu.int/en/ITU-T/Pages/default.aspx

Operation

As stated above, the clock signal is transmitted on Layer 1 (physical) and the Synchronization
Status Messaging (SSM) is transmitted on layer 2 (data link). If SyncE is enabled, you would use
syncestatx, where x is network port 0 (eth0) or 1 (eth1) for the SSM code.
Verify that the network settings have been configured and tested using netconfig. Once the network has been configured, the Meridian II will synchronize the Ethernet and begin to transmit theSSM code.
The Ethernet Synchronization Messaging Channel (ESMC) contains the clock Quality Level (QL)with the embedded SSM code. The ESMC data will be sent at a rate of once per second.

Status

The syncestatx command (where x is network port 0 (eth0) or 1 (eth1)) allows you to query
the status of SyncE. When the clock is locked, the ESMC and syncestatx will report the quality
level of QL-PRC and set the SSM code. When the clock is not locked (TFOM > 4), syncestatx
will report the quality level of QL-DNU and set the SSM code.
QL-PRC: Primary Reference Clock that is defined in ITU-T G.811.
QL-DNU: Do Not Use this signal for synchronization.
For example:
Command:syncestat0
Meridian II reply:SSM Code: QL-PRC
orCommand:syncestat1
Meridian II reply:SSM Code: QL-DNU

Disable the
SyncE Protocol

The instructions below assume that the SyncE Option has been installed on your Meridian II port 0(eth0). To check, see the section titled Option at the beginning of this chapter.
To disable SyncE on port 0 issue the following command:
chmod -x /etc/rc.d/rc.synced0

Copy the rc.synced0 file to the non-volatile FLASH area like this:138

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cp -p /etc/rc.d/rc.synced0 /boot/etc/rc.dThen:rebootOnce SyncE has been disabled, it will no longer execute. However, the web interface will still show
SyncE and the syncestat0 command will still exist on the system.

Re-Enable SyncE

To re-enable SyncE on port 0 (eth0), remove the rc.synced0 file from the /boot/etc/rc.d directory as
shown below:
rm /boot/etc/rc.d/rc.synced0

Then:
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Chapter Thirteen

Front-Panel Keypad and Display
This section describes the Meridian II front-panel user interface which consists of a graphic vacuumfluorescent display (VFD) and keypad. The keypad and display provide a convenient interface thatallows you to quickly check the operation of the instrument and set up many control parameters. If
desired, you can disable the keypad EDIT key to prevent unauthorized tampering. When disabled, allstatus and control parameters are available for reading only.

Display Description

Keypad Description

The display consists of a graphic 16 x 280 dot-matrix vacuum-fluorescent array. The VFD technology
offers very readable alphanumeric characters with variable font sizes. Time information is readableat distances in excess of 15 feet. The keypad consists of an eight-key switch assembly designed toallow easy parameter selection and control.

The front-panel keypad consists of eight switch keys identified as follows:
ENTER:
BACK:
EDIT:
HELP:
LEFT arrow:
RIGHT arrow:
DOWN arrow:

UP arrow:

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Select a menu item or load a parameter when editing.
Return to previous display or abort an edit process.
Edit the parameter currently in view.
Display context-sensitive help information.
Select a new item to the left.
Select a new item to the right.
Scroll through parameter values in edit displays or through help lines in help
displays. In all other displays this key has a secondary function where it will
operate like the ENTER key to select menu items.
Scroll through parameter values in edit displays or through help lines in help
displays. In all other displays this key has a secondary function where it will
operate like the BACK key to return to the previous display.

Meridian II User ManualCHAPTER THIRTEEN

Display and Keypad
Operation

The display menus are organized as shown below:
Time / Status
Display
Main Menu
CPU
Statistics

ReceiverMenu

Faults
Menu

I/O
Menu

Network
Menu

NTP
Menu

PTP
Menu*

Clock
Menu

Display
Setup

FirmwareInformation

About
EndRunClock Menu
Time Mode
Setup

Local Offset
Setup

Hours Display DST
FormatSetup

NTP Menu
NTP
StatusI/O Statistics

Broadcast/Multicast
Setup

Network Menu
Network
IPv4

Network
IPv6

MAC
Address

RebootOptionSlot 1

OptionSlot 2

OptionSlot 3I/O Menu
SystemI/O

CPU Module
I/O

OptionSlot 4

CPU I/O Menu

Faults Menu
SystemFaults

ReceiverFaultsAntenna Fault
Mask

OptionSlot 5Signal Fault
Mask

TFOM
Fault Level

I/O-A

I/O-B

I/O-C Option

System I/O Menu
1 PPS
Pulse Width

Time CodeFormatDDS
Selection*

SerialTime
Setup*

InhibitMode

Receiver Menu
GPS Receiver
StatusSatellite Vehicle
Information

Reference
Position

Last Position
Fix

UTC
Information

Dynamic
Mode

Oscillator
StatusClock
Calibration

RTIC** Optional features. These menu items may not be present.

Traversing the Display Structure

After power initialization the welcome message will appear. Press any key to go to the Time/Status
display, which is described below. From the Time/Status display, press ENTER or DOWN to go to
the Main Menu. As illustrated in the diagram above, several status and setup displays are accessible
from the Main Menu. To go downward through the structure use the RIGHT and LEFT arrow keys
to highlight a selection and then press ENTER or DOWN. To go back up through the structure press
BACK or UP to return to the previous display.

Editing

To modify a parameter, go to the appropriate display and push EDIT. The edit display will appear
and the modifiable parameter value is highlighted. Use UP and DOWN to scroll through all the possible parameter values. When editing a sequence of numbers, use LEFT and RIGHT to select otherdigits. When the parameter is correct, press ENTER to load the new value. All entered values are
stored in non-volatile FLASH and restored after a power cycle. If you wish to abort the edit process,press BACK. This will return you to the previous display and the parameter will remain unchanged.
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Keypad EDIT Lockout

As a security feature, you can disable all editing processes done through the front-panel keypad. Do
this to prevent unauthorized modification of the instrument. When the EDIT key has been disabled, awarning message will appear whenever a user tries to edit a parameter. To enable the lockout feature
use the lockoutkp command as described in Chapter 3 - Console Port Control and Status. The
lockout feature will prevent editing only, the displays are always available for viewing.

Using Help

Press HELP at any time to read the context-sensitive help messages. Use UP and DOWN to scroll
through the help message. Press the HELP key a second time to exit Help (or press BACK).

Shortcut Menu

The Shortcut Menu allows the user quick access to particular displays from the Time/Status display.
The displays available through the Shortcut Menu are the Receiver Status, GPS Reference Position,
Faults, and NTP Status. To select the Shortcut Menu, press ENTER for one second while viewing theTime/Status display.

Detailed Display
Descriptions

Time/Status

The Time/Status display provides all the information necessary to determine that the instrument isworking correctly:

12 : 59 : 45

U
TC

Jun 15, 2015

Receiver- LKD

TFOM - 3

Sys Stat- OK

Time-of-Day:

The large numeric digits shown on the left side of the display indicate thecurrent time-of-day.

Time Mode:

The indicator next to the time digits identifies the time mode as being UTC, GPSor LOC (for Local time). If the user selects Local time in the 12-hour mode, an
AM or PM indicator will appear instead of LOC.

Date:

Current month, day and year.

TFOM:

A detailed explanation of TFOM is in Appendix A - Time Figure-of-Merit.
Briefly, TFOM indicates clock accuracy where:
3time error is < 100 ns
4time error is < 1 us
5time error is < 10 us
6time error is < 100 us
7time error is < 1 ms

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Receiver Status:

GPS Subsystem status as follows:
WRM:
Warmup period for units with oscillator upgrades.
ACQ:
Acquring. Searching for a signal.
LKG:
Locking to the GPS signal.
LKD:
Locked. Fully synchronized to signal.

System Status:

Indicates either OK or flashing FAULT. A fault status indicates that one or moreof the built-in fault checking processes has detected an error condition. See
Faults: System in this chapter for more information.

An alternate Time/Status display can be viewed by pressing the right arrow key. You can go back to
the original Time/Status display by pressing the left arrow key.

181 : 12 : 59 : 45

U
TC

Receiver- LKD
Sys Stat- OK

Main Menu

Press ENTER from the Time/Status display to select the Main Menu display. The Main Menu provides access to the following displays: CPU_Stat, Receiver, Faults, Network, NTP, Clock, Display,
Firmware, and About. In addition, Sys_I/O, CPU_I/O and PTP displays may be present if yourMeridian II has these optional features.

CPU Status

This displays shows measured CPU parameters such as: temperature, free memory, and load average.

Receiver Menu

The Receiver Menu is selected from the Main Menu and provides access to Status, SV_Info, Ref_
Pos, Last_Fix, UTC_Info, Dyn_Mode, Osc_Stat and Calibrate. These displays are described in detailbelow.
Receiver: Status (GPS Subsystem/Receiver Status)
This display provides status information for the GPS Subsystem and Receiver. Press DOWN toscroll through all the information.
Subsystem State:

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This shows the current state of the GPS Subsystem/Receiver as follows:
WRM:
Warmup period for units with oscillator upgrades.
ACQ:
Acquring. Searching for a signal.
LKG:
Locking to the GPS signal.
LKD:
Locked. Fully synchronized to signal.
The GPS Subsystem is synchronized to the signal and it isdisciplining the system oscillator to remove frequency
and time errors.

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TFOM:This is a value between 3 and 9 and indicates clock accuracy.
A detailed explanation of TFOM is in Appendix A - TFOM.

Receiver State:This shows the current state of the GPS Receiver as follows:
ACQ:
Acquring. Searching for a signal.
LKG:
Locking to the GPS signal.
LKD:
Locked. Fully synchronized to signal.
The GPS Receiver is synchronized to the signal and it isproviding valid measurement data to the GPS Subsystem pro
cessor.

# of SVs:

This shows the number of currently tracks Satellite Vehicles from 0 to 12.

AGC

This is the automatic gain control DAC byte, 0 to 255, with larger numbers
implying higher RF gain. With good signal conditions this value is typically 125
to 200.

Avg C/No:

The carrier-to-noise ratio is an indicator of the GPS signal quality. This
number typically ranges from 39 to 50 dB when the instrument is locked.

SV ID#:

This field lists the satellite vehicles that are currently being tracked.

Receiver: Satellite Vehicle Information (SV_Info)
This displays shows the channel number, SV number, azimuth, elevation and the carrier-to-noise ratio(C/No) for all 12 channels of the 12-channel GPS Receiver. SV number 0 is an invalid number andindicates that no satellite is being tracked on that channel. Valid SV numbers range from 1 to 32.
Azimuth and elevation are in degrees and C/No is in dB.
Receiver: Reference Position (Ref_Pos)
This display shows the current GPS reference position and allows you to enter a position, if desired.
The GPS reference position is the position of the GPS antenna. Accurate position is necessary to
generate precise time and frequency outputs.
The position is shown as latitude, longitude and elevation. Latitude and longitude are shown ashemisphere (North, South, East, West), degrees, minutes and seconds. Elevation is shown in meters
above the WGS-84 ellipsoid. By scrolling down, the RMS PDOP and Average Count are shown for
the averaged position. These will be zero if the source of the position is not “average”. A complete
average consists of 28800 fixes.
The source field (SRC) indicates the source of the position information. Possible values are “unknown”, “average” and “user”. When first installed, the position source will be “unknown”. Itchanges to “average” after the receiver has computed the first 3-dimensional position fix. The position continues to be averaged for about 24 hours. Computation requires that a minimum of 4 ormore satellites be in view.
With a rooftop antenna installation that has an unobscured view of the sky, the instrument will determine position automatically. Once determined, the position information is saved in non-volatile
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FLASH and will be restored after a power outage. After position has been determined, the instrument
can achieve time lock with only one satellite.
In some situations, visibility of the sky is limited and the unit may not be able to determine its position. In this case you must determine an accurate WGS-84 position by other means and input it either
through the serial interface or via the front panel. In addition to loading a new accurate reference
position, you can also invalidate an existing one by setting the position source to unknown. This will
force the instrument to re-establish a new reference position using the GPS satellite constellation.
Push the EDIT key to start the process. First, select the reference position source:
Unknown: Selecting “unknown” will cause the CALCULATE NEW POSITION AVERAGE
confirmation display to appear. Select YES. The front panel will return to the GPS
Reference Position display. This action will force the unit to re-establish a new reference
position. Once the receiver has computed a new accurate reference position the position
source will change from “unknown” to “average”.
User:

Selecting “user” will allow you to enter a position. It is very important that the newreference position be accurate. Refer to Appendix E - Installing the GPS Antenna,
GPS Reference Position for detailed instructions on how to obtain an accurate reference
position for your location.

Receiver: Last Fix Position (Last_Fix)
This display provides the last computed GPS position. When tracking four or more satellites, theGPS Receiver provides a 3D-position fix. The last-fix position is normally less accurate than the reference position, but it does provide a good indication that the receiver is working properly. Position
is provided in latitude, longitude and height. By scrolling down, the PDOP, HDOP, VDOP and TDOP
along with the Out-of-Range count are shown.
Receiver: UTC Information (UTC_Info)
This display shows the UTC Information which includes leap seconds (LS) and future leap seconds(LSF) for the week number (WN_lsf) and day number (DN) displayed. It also shows the IS-GPS200 almanac parameters which are used to calculate the offset between UTC and GPS time. These
include parameters for determining leap seconds and the parameters for calculating the small residual
offset between the GPS master clock ensemble and UTC(USNO). This latter value is typically lessthan 10 nanoseconds. Press HELP to read more detailed information on the fields shown in thisdisplay.
Receiver: Dynamic Mode (Dyn_Mode)
The GPS dynamic mode setting affects the position value used by the system to derive accurate timesynchronization. In dynamic mode, the average position is displayed as the current position, in otherwords - there is no position averaging. Dynamic mode is suitable for shipboard applications only.
It is important to set the mode to “OFF (static installation)” when the instrument is in a static installation. This is the factory-default setting. Set the mode to “ON (dynamic installation)” ONLY if the
instrument is installed on a moving platform such as a ship.

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Receiver: Oscillator Status (Osc_Stat)
This display provides the system oscillator status information which includes oscillator type andelectronic frequency control status. The oscillator control DAC value indicates the frequency control
setting. The system automatically sets this value to remove frequency errors. Values may range from0 to 1,048,575. Values close to the minimum or maximum will set the DAC fault flag that will appear
in the fault status display. The Time/Status display will also indicate a fault condition.
The oscillator type indicates the oscillator that is installed. Possible oscillator types are:Temperature-compensated crystal oscillator (TCXO)
Medium-stability oven-controlled oscillator (MS-OCXO)
High-stability oven-controlled oscillator (HS-OCXO)
Ultra-stable oven-controlled oscillator (US-OCXO)
Rubidium oscillator (Rb)
Ultra-Stable rubidium oscillator (US-Rb)
Receiver: Calibrate
Calibrate is used to compensate for the propagation delay between the GPS antenna and the Meridian
II GPS receiver. This is required for the Meridian II to synchronize with maximum accuracy to UTC.
See Appendix E - Installing the GPS Antenna, Calibrate Your Receiver for more details.
Receiver: RTIC (Optional)
This optional display is used for control and status of the RTIC Option. See Chapter 11 - Real-Time
Ionospheric Corrections for more information.

Faults Menu

The Faults Menu is selected from the Main Menu and provides access to view the System Faults andto set fault masks for the Antenna Fault and the Signal Loss Fault.
Faults: System
All system faults are shown on this display and their current status, either OK or FAULT. When afault condition exists the FLT indicator will flash.
These fault indicators are the same as the corresponding bit positions shown in the gpsstat fault status word. (See Chapter 3 - Console Port Control and Status for information on gpsstat.) Unused
bit positions show on the display as ‘---’. The faults are listed below. For details on each fault, see
Appendix G - System Faults.
FLSH
FPGA
SIG
DAC
RCVC
REF
POLL
RCVF
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GPS Subsystem FLASH Writes
GPS Subsystem FPGA Configuration
GPS Signal
System Oscillator DAC
GPS Receiver Communication
GPS Reference Time
Subsystem Communication
GPS Receiver
Meridian II User ManualCHAPTER THIRTEEN

PLL
ANT
OPT
PWR
SECPS
PRIPS
5071A

System Oscillator PLL
GPS Antenna
Option Module
System Power/Configuration
Secondary Power Supply (option)
Primary Power Supply (option)
5071A Module (option)

Faults: Receiver
All GPS Receiver faults are shown on this display and their current status, either OK or FAULT.
When a fault condition exists the FLT indicator will flash. These fault indicators are the same as thecorresponding bit positions shown in the gpsstat fault status word FLTR. (See Chapter 9 - Console
Port Control and Status for information on gpsstat.) The faults are listed below. For details oneach fault, see Appendix G - System Faults.
FLSH
FPGA
SIG
DAC
OSC
REF
SYN1
SYN2
PLL
OPEN
SHRT

Receiver FLASH Writes
Receiver FPGA Configuration
GPS Signal
Receiver Oscillator DAC
Receiver Oscillator
GPS Reference Time
Local Oscillator Synthesizer Tuning
Local Oscillator Synthesizer
Oscillator Phase Lock
GPS Antenna is open-circuit
GPS Antenna is short-circuit

Faults: Antenna Fault Mask (AntFltMask)
This setting allows you to prevent the antenna fault from creating an alarm conditon. Some installations may need to mask this fault due to special antenna situations like splitters or DC blocks that
confuse the antenna detection circuit.
Faults: Signal Loss Fault Mask (SigFltMask)
This setting allows you to prevent a signal loss fault from creating an alarm condition. Some installations may need to mask this fault when operating the NTP server as a Stratum 2 server.
TFOM Fault Level
This is the threshold at which a signal loss fault will be asserted. See Appendix A - Time Figure of
Merit for more information. By changing the TFOM Fault Level you control the point at which thetime error will produce a signal loss fault, which then creates an alarm condition. The factory default
setting is 9, which is the maximum TFOM value.
Faults: Dual Power Input Fault Alarm Masks (PwrFltMask) (Optional)
This setting allows you to prevent a primary or secondary power supply fault from creating an alarm
condition. See Chapter 10 - Options, Masking Dual Power Supply Fault Alarms for more information.
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I/O Menu

The I/O Menu provides access to the information and user settings related to the rear-panel I/O connectors. In addition to the CPU Module, each Meridian II has five plug-in option slots. Each slot
has an associated display for status and setup. Slots are numbered left to right with Slot 1 being thefirst plug-in location next to the CPU Module. If an option slot is empty, the display will indicate
Empty(1-5). When an option card is installed, the display will show OptCard(1-5). Select CPU-I/O toview status and setup information for the CPU Module outputs. Select an option slot (i.e. OptCard4)
to view status and setup information for that particular option card.
If your Meridian II is a 2U chassis with dual power supplies, then the display will show two additional option cards (6 and 7). Refer to Chapter 10 - Rear-Panel I/O for more information regarding
the various option modules.
System I/O Menu (Sys_I/O)
The Sys_I/O Menu is used for viewing and configuring system-wide output signals. System signals
are the 1PPS, time code, optional DDS and optional SerialTime. See Chapter 10 - Rear-Panel I/O
for more information. The Inhibit function allows you to prevent the timing signals (such as 1 PPS
and time code) from being output until the Meridian II has achieved a first-time lock status.
CPU Module I/O Menu (CPU_I/O)
The CPU_I/O Menu is used for viewing the CPU Module output signals. I/O-A and I/O-B are always
used. I/O-C is available for an optional output in a 1U chassis. I/O-C through I/O-F are available ina 2U chassis. If an optional Programmable Pulse Output (PPO) is present, then you may change the
PPO setting by pressing EDIT. See Chapter 10 - Rear-Panel I/O, Standard I/O and CPU Module
Options for more information on the CPU Module options.

Network Menu

The Network Menu is selected from the Main Menu and provides access to Network4, Network6,
MAC Address and REBOOT displays which are described below.
Network: Network4
This display provides the ability to view and modify the IPv4 network settings. The parameters
include Dynamic Host Configuration Protocol (DHCP), IP address, gateway, netmask and domainname server (DNS) settings. Enable DHCP to allow automatic system configuration of the network
interface. When DHCP is disabled the user must provide address information.
Network: Network6
This display provides the ability to view and modify the IPv6 network settings. Refer to Chapter 8- IPv6 Information.
Network: MAC Address (MAC_Addr)
This display provides the media access control (MAC) address for both network ports (eth0 andeth1).

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Network: REBOOTThis is a way to reboot the Meridian II and is necessary after you’ve finished configuring the network
parameters. Until you do this, the network parameters that are shown will be the active settings, NOT
the new settings. The new settings will become active after you reboot.

NTP Menu

The NTP Menu is selected from the Main Menu and provides access to the Status, I/O Statistics and
Setup displays described below:
NTP: Status
This display provides information associated with the NTP Subsystem.
Stratum:

Source:This stratum field has three possible values:
Stratum 1:
The server is fully synchronized and accurate.
Stratum 2:
The server is synchronized to a Stratum 1 server.
Stratum x:
The server is synchronized to a Stratum x server.
Stratum 16:
The server is unsynchronized. NTP clients will not use a Stratum 16
server.
The synchronization source is named here. For the Meridian II the source is GPS,
IP address of upstream source, or none.

Offset:The NTP offset indicates the accuracy of the NTP system clock relative to the GPS
Subsystem clock. Initially, if the offset between the NTP system clock and the GPS
Subsystem clock is large the display will indicate “not available”. After the GPS
Subsystem locks, the NTP clock will synchronize to the GPS Subsystem. Once
synchronization is complete, the typical offsets will range over approximately+/- 1 microsecond.

LI Bits:

Shows the status of the leap indicator bits as sent by the Meridian II time server to theclients in the NTP reply packets. Leap seconds occur every 2-3 years.
Possible indicator values are:00:
Normal, locked operation.
01:
Leap second insertion event will occur after 23:59:59 UTC.
11:
Fault. Unsynchronized state.

NTP: I/O Statistics (I/O_Stats)This display shows some key information regarding the operation of the NTP daemon. The information includes the time since reset and the counts of received, sent and dropped packets, and the sent
packet rate.

NTP: Setup
This display provides access to the NTP broadcast and multicast settings and provides you with aconvenient means of checking the current configuration and allows limited setup. You may also
perform a more complete broadcast/multicast configuration via a telnet or ssh session or the local

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RS-232 console using the ntpconfig utility. This utility provides a more secure means of setup andso is more complete. It will allow you to select keys and identify trusted keys.
This display will indicate that the mode is broadcast4, broadcast6, multicast4, multicast6 or disabled.
It allows IPv4 or IPv6 configuration of either broadcast or multicast mode with selection of the broadcast address, multicast time-to-live (TTL) and trusted key for MD5 authentication. The broadcast/multicast mode may also be disabled.
Broadcast ModeIn this mode the broadcast address is displayed. If MD5 authentication is
selected the trusted key number will also be displayed.

Multicast Mode

The multicast address must be 224.0.1.1 or ff05::101. Multicast may also use
MD5 authentication. If selected, the trusted key number will also be displayed.

Press EDIT to change the broadcast/multicast settings. Each of the edit windows has help information available to guide you through the setup process. Note that changing the NTP multicast/broadcast settings does not take effect until the system reboots. The new parameters are loaded to thentp.conf file in the /boot/etc/ directory. Only the broadcast line in the ntp.conf file is modified. The
final display in the edit sequence requires confirmation of your intent to change the instrument settings. Once confirmation takes place, the instrument will reboot.

PTP Menu (Optional)

The PTP Menu is used for control and status of the PTP/IEEE-1588 option. See Chapter 9 - PTP/
IEEE-1588 for more information.

Clock Menu

The Clock Menu provides access to the parameters related to timekeeping. These are Time_Mode,
Time_Zone, Hour_Mode, and DST. These displays are all described below.
Clock: Time Mode
Time mode defines the time format used for the front-panel time display and, if installed, the optional
Time Code or Serial Time output. The time mode does not affect the NTP output, which is always
UTC. Possible values for the time mode are GPS, UTC, and Local time. GPS time is derived fromthe GPS satellite system. UTC is GPS time minus the current leap second correction. Local time is
UTC plus time zone offset and DST. The time zone and DST displays are described below.
Clock: Time Zone
The time zone is used in calculating the current Local time when the time mode is set to Local (seetime mode above). Press the EDIT key to change the value. Enter a negative offset for time zones
west of the Greenwich meridian, and a positive offset for time zones to the east. If enabled, DST will
add an additional hour.

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Clock: Hour Mode
Hour mode affects the front-panel time display and is active only when the time mode is set to Local
time. Hours-display selections are either 12-hour format (1-12 hours with AM/PM indicator) or 24hour format (0-23 hours).
Clock: Daylight Saving Time (DST)DST is used in calculating the current Local time when the time mode is set to Local. When thetime mode is Local this display will allow you to enable or disable DST by pressing EDIT. If DST isdisabled then any previously set start and stop times will be ignored. If DST is enabled then the startand stop times can be set by pressing the arrow keys to scroll and then ENTER. DST is active within
the start-stop interval and adds one hour to the Local time. If DST is active the display will show anactive indicator.

Display Setup

This display is selected from the Main Menu and contains parameters related to the functioning of thefront-panel display. There are two parameters -- an intensity setting and a screensaver setting. The
intensity setting allows you to set the brightness level of the VFD. Display intensity ranges from
12% to 100%. The screensaver capability allows you to increase the usable life of the display beyond
the rated 100,000 hours. When the screensaver capability is enabled, the intensity will be reduced tohalf of its normal operating intensity when the unit has not detected a keypress for one hour. Press
EDIT to modify the intensity and screensaver settings.

Firmware

The Firmware display is selected from the Main Menu and provides version information for theapplication software running on the GPS Receiver, the GPS Subsystem and the Linux Subsystem(Linux Root File System and Linux Kernel). The serial number of the Meridian II is also shown.
Use UP and DOWN to toggle between the information windows.

About

The About display is selected from the Main Menu and provides contact information for EndRun
Technologies. The website and toll-free phone number are listed.

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Appendix A

Time Figure of Merit (TFOM)This appendix describes the Time Figure of Merit number. The TFOM number indicates the level ofaccuracy that should be included in the interpretation of the time-of-day and ranges from 3 to 9:
3
4
5
6
7
8
9

time error is < 100 nanoseconds
time error is < 1 microseconds
time error is < 10 microseconds
time error is < 100 microseconds
time error is < 1 milliseconds
time error is < 10 milliseconds
time error is > 10 ms, unsynchronized state if never locked to GPS

In all cases, the Meridian II reports this value as accurately as possible, even during periods of
GPS signal outage where the Meridian II is unable to directly measure the relationship of its timing
outputs to UTC. During these GPS outage periods, assuming that the Meridian II had been synchronized prior to the outage, the Meridian II extrapolates the expected drift of the Meridian II timing
signals based on its knowledge of the characteristics of the system oscillator - either the Temperature
Compensated Crystal Oscillator (TCXO), Oven Controlled Crystal Oscillator (OCXO) or Rubidium
oscillator. The extrapolated TFOM is based on a conservative estimate of the performance of the oscillator and should be considered ‘worst case’ for a typical benign ambient temperature environment.
Due to this extrapolation behavior, after initial synchronization, brief periods without GPS satellite
visibility will not induce an immediate alarm condition. (Removal of the antenna to simulate this will
induce an immediate alarm, however.) If the condition persists for long enough periods, you should
see the TFOM character change to indicate a gradually deteriorating accuracy of the timing outputs.
If the signal loss condition persists longer, then the final, unsynchronized state will eventually bereached. If the Meridian II is unable to re-synchronize within one hour after reaching this state, theAlarm LED will light and the faultstat command will show a No Signal Time-Out fault.
Once the Meridian II reaches the unsynchronized TFOM state, then the Network Time Protocol(NTP) daemon will report that it is running at stratum 16 and the leap indicator bits will be set to thefault state. NTP clients will recognize this and cease to use the unsynchronized server.

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Appendix B

Upgrading the Firmware
Periodically, we make bug fixes and enhancements to our Meridian II product line. The Meridian II
firmware is freely available on our website at the link shown below. You may securely upgrade yourMeridian II firmware via the HTTPS interface or the console port (network/serial).
endruntechnologies.com/support/software-upgrades/meridian-ii

NOTE
The Meridian firmware consists of several different binary files. You may only need one or two of them.
The revision history on our website will tell you which files need to be upgraded. The firmware image files
are for the Linux RFS (root file system), the Linux Kernel, GPS Subsystem and the GPS Receiver. (The GPS
Receiver FPGA is rarely, if ever, upgraded.)Upgrade via the
HTTPS Interface

Software upgrades via the HTTPS interface are simple, with your choice of two methods:
1. If your Meridian II has access to the Internet, the HTTPS interface can automatically retrieve theappropriate files from the FTP server at endruntechnologies.com to temporary locations on the Meridian II. You will need to enter “root” as the user name and enter root’s password. Then follow the
prompts from the HTTPS interface to complete each upgrade as needed.

IMPORTANTThe domain name server IP address is required by the Apache web server. When using netconfig(see Chapter 3 - Console Port Control and Status) to configure the TCP/IP parameters be sure toconfigure a name server. Only one name server is required but two gives some redundancy. The HTTPSInterface will not operate properly if this is configured incorrectly.
The following picture shows the Linux RFS (root file system) Upgrade page. All fields are filled inwith the default values needed to download the appropriate firmware image from the EndRun Technologies website. You can use these default values unless you want to point to a different FTP server.

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2. If your Meridian II does not have access to the Internet, you must first download the appropriate
file(s) from the EndRun Technologies website to the computer that you will be using later to accessthe Meridian II via its HTTPS interface. Use this link to get the file(s) you want:endruntechnologies.com/support/software-upgrades/meridian-ii

After saving the file(s), use the Meridian II HTTPS interface to select one or more for upload to
the Meridian II. Then follow the remaining prompts from the HTTPS interface to complete theupgrade(s). (You will need to enter “root” as the user name and enter root’s password.)

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Upgrade via theConsole Port

In order to upgrade via the console port (network or serial) you will need to first download the appropriate firmware image from our website. The Meridian II firmware consists of four different binary
files. You may only need one or two of them. The revision history on our website will tell you whichfiles need to be upgraded. The firmware image files are for the Linux RFS (root file system), theLinux Kernel, the GPS Subsystem and the GPS Receiver. Here is the website link:endruntechnologies.com/support/software-upgrades/meridian-ii

Performing the Linux RFS Upgrade
NOTE TO LINUX GEEKSThere are two FLASH disk partitions which hold the compressed Linux root file system images. These
partitions are raw FLASH blocks, have no file system and may not be mounted. They are accessed throughlow-level device drivers. To protect the factory root file system from accidental erasure or over-writing, theupgrade utilties you will be using will only access the upgrade root file system partiton. When performing
an upgrade, you will be erasing and then copying the new image to this device.

First you need to download the Linux RFS firmware from the EndRun website to a place on yournetwork which is accessible to the Meridian II. The link to the Meridian II upgrade page is shown
above.

CAUTION
Some browsers will automatically unzip the file when downloading from the website. Please make surethat the downloaded file size matches what the website says it should be. Upgrading the partition with a
too-large file size will cause problems.

Transfer File to Meridian II
You may transfer the file to your Meridian II using either ftp or scp. If you are using ftp, transfer
the previously downloaded file using binary transfer mode from the remote host to this specific fileon your Meridian II: /tmp/rootfs.gz. The root file system image will be named with the software partnumber and version like: 6010-0067-000_3.00.gz. When following the instructions below, substitutethe name of the actual root file system image that you are installing for 6010-0067-000_3.00.gz. Issue these commands from the console of your Meridian II:
ftp remote_host{perform ftp login on remote host}bin{set transfer mode to binary}get 6010-0067-000_3.00.gz /tmp/rootfs.gz {transfer the file}quit{close the ftp session after transfer }157

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If you are using scp, you may open a command window on the remote computer and securely transfer the root file system image from the remote computer to your Meridian II. A command like thisshould be used:
scp –p 6010-0067-000_3.00.gz root@host.your.domain:/tmp/rootfs.gz

Now issue the following command to the Meridian II console to initiate the upload:
upgraderootfs

Next, update the default file system partition by issuing this command to your Meridian II console:
updaterootflag 1

You should see this line displayed:
Default Root File System now set to: UPGRADE

Finally, reboot the system by issuing this command at the shell prompt:
rebootWait about 90 seconds for the system to shutdown and reboot. Then log in to the Meridian II using
telnet or ssh. If all has gone well, you should be able to log in the usual way. After you haveentered your password, the system version message will be displayed. You should notice that it now
indicates the software version and date of the upgrade that you previously downloaded. You can also
check this at any time by issuing
sysversion

which will cause the system version message to be re-displayed.
You can also check to see which root file system image the system is currently booted under by issuing this command at the shell prompt:
sysrootfs

Which should cause this to be printed to the console:
BOOTED ROOT FILE SYSTEM IMAGE = 1 (Upgrade)

If so, and your unit seems to be operating normally, you have successfully completed the root filesystem upgrade. If your unit does not boot up successfully, and you are not able to telnet or ssh
into the system after 90 seconds, then there has been some kind of problem with the root file system
upgrade. It is possible that the file downloaded was corrupt or that you forgot to set your FTP download file mode to binary when downloading the file--either from the EndRun Technologies website orwhen transferring it to the Meridian II.

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Recovering from a Failed RFS Upgrade
To restore your Meridian II to a bootable state using the factory root file system, you must use theserial I/O port and reboot the Meridian II by cycling the power. Refer to Chapter 2 – Basic Installation, Connect the Serial I/O Port and Test the Serial I/O Port for setup details. When you haveconnected your terminal to the serial I/O port, apply power to the Meridian II.
Pay close attention to the terminal window while the unit is rebooting. After the Linux bootloader
displays the message
Default kernel: FACTORY
To override and boot the UPGRADE version of the kernel,
type UPGRADE within 5 seconds.....
Booting with FACTORY Kernel
Default Root File System: UPGRADE
To override and boot the FACTORY version of the Root File System,
type FACTORY within 5 seconds

you must begin typing “factory” within five seconds to let the bootloader know that you are going tooverride the default root file system. After you hit <enter> the bootloader will boot the factory root
file system. Watch the rest of the boot process to make sure that you have successfully recovered. If
the system boots normally, then you should resolve the problems with the previous root file system
upgrade and re-perform it.

Performing the Linux Kernel UpgradeFirst you need to download the Linux Kernel firmware from the EndRun website to a place on yournetwork which is accessible to the Meridian II. The link to the Meridian II upgrade page is shown
above.
Transfer File to Meridian II
You may transfer the file to your Meridian II using either ftp or scp. If you are using ftp, transfer
the previously downloaded file using binary transfer mode from the remote host to this specific fileon your Meridian II: /tmp/kernel.gz. The kernel image will be named with a software part number
like: 6010-0064-000_2.00.uImage. When following the instructions below, substitute the name of theactual kernel image that you are installing for 6010-0064-000_2.00.uImage. Issue these commands
from the console of your Meridian II:
ftp remote_host{perform ftp login on remote host}bin{set transfer mode to binary}get 6010-0064-000_2.00.uImage /tmp/kernel.gz{transfer the file}quit{close the ftp session after transfer }If you are using scp, you may open a command window on the remote computer and securely transfer the kernel image from the remote computer to your Meridian II. A command like this should be
used:
scp –p 6010-0064-000_2.00.uImage root@host.your.domain:/tmp/kernel.gz

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Now issue the following command to the Meridian II console to initiate the upload:
upgradekernel

Next, update the default file system partition by issuing this command to your Meridian II console:
updatekernelflag 1

You should see this line displayed:
Default Kernel now set to: UPGRADE

Finally, reboot the system by issuing this command at the shell prompt:
rebootWait about 90 seconds for the system to shutdown and reboot. Then log in to the Meridian II using
telnet or ssh. If all has gone well, you should be able to log in the usual way. You can check therunning kernel version at any time by issuingkernelversion

which will cause the kernel version message to be displayed.
You can also check to see which kernel image the system is currently booted under by issuing thiscommand at the shell prompt:
syskernel

Which should cause this to be printed to the console:
BOOTED KERNEL IMAGE = 1 (Upgrade)

If so, and your unit seems to be operating normally, you have successfully completed the kernel
upgrade. If your unit does not boot up successfully, and you are not able to telnet or ssh into thesystem after 90 seconds, then there has been some kind of problem with the kernel upgrade. It is
possible that the file downloaded was corrupt or that you forgot to set your ftp download file modeto binary when downloading the file--either from the EndRun Technologies website or when transferring it to the Meridian II.
Recovering from a Failed Kernel Upgrade
To restore your Meridian II to a bootable state using the factory kernel, you must use the serial I/O
port and reboot the Meridian II by cycling the power. Refer to Chapter 2 – Basic Installation, Connect the Serial I/O Port and Test the Serial I/O Port for setup details. When you have connectedyour terminal to the serial I/O port, apply power to the Meridian II.
Pay close attention to the terminal window while the unit is rebooting. After the Linux bootloader
displays the message

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Default kernel: UPGRADE
To override and boot the FACTORY version of the kernel,
type FACTORY within 5 seconds

you must begin typing “factory” within five seconds to let the bootloader know that you are going tooverride the default kernel. After you hit <enter> the bootloader will boot the factory kernel. Watch
the rest of the boot process to make sure that you have successfully recovered. If the system boots
normally, then you should resolve the problems with the previous kernel upgrade and re-perform it.

Performing the GPS Subsystem UpgradeThis section has instructions for upgrading the GPS Subsystem. If you want to upgrade the GPS
Receiver, see the section below called Performing the GPS Receiver Upgrade.
First you need to download the GPS Subsystem firmware from the EndRun website to a place on
your network which is accessible to the Meridian II. The link to the Meridian II upgrade page isshown above.

CAUTION
Before proceeding, use the gpsversion command to confirm that the firmware number of your GPS
Subsystem is: F/W 6010-0076-000
If it is different (for example: F/W 6010-0076-101), then contact the factory.
You may transfer the file to your Meridian II using either ftp or scp. If you are using ftp to perform the upgrade, transfer the previously downloaded file using binary transfer mode from the remote
host to this specific file on your Meridian II: /tmp/subsys.bin. The GPS Subsystem image will be
named with the software part number and version like: 6010-0076-000_3.01.bin. When following
the instructions below, substitute the name of the actual GPS Subsystem image that you are installingfor 6010-0076-000_3.01.bin. You will be transferring the file to a temporary file, /tmp/subsys.bin on
your Meridian II.
ftp remote_host{perform ftp login on remote host}bin{set transfer mode to binary}get 6010-0076-000_3.01.bin /tmp/subsys.bin{transfer the file}quit{close the ftp session after the transfer }If you are using SSH to perform the GPS Subsystem upgrade, you may open another command
window on the remote computer and securely transfer the GPS Subsystem image to /tmp/subsys.binusing scp from the remote computer. A command like this could be used:
scp –p 6010-0076-000_3.01.bin root@host.your.domain:/tmp/subsys.bin

Now issue the following command to the Meridian II console to initiate the upload:
upgradesubsys

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This command performs the file transfer to the GPS Subsystem. You will see a file transfer progressmessage while it is performing the transfer. After it completes, wait about 40 seconds and issue thiscommand to check the GPS Subsystem version:
gpsversion

You should see a message like this:F/W 6010-0076-000 Ver 3.01 - FPGA 6020-0016-000 Ver 01 - JAN 12 15:30:58 2013

The firmware version should match that of the binary file that you uploaded.
Problems with the GPS Subsystem Upgrade
Should you have difficulties with the upgrade due to a corrupt file, power failure during upload, orother accident, do not be alarmed. Even though you may have lost the existing application program,the GPS Subsystem bootloader program will remain intact. Correct any problem with the binary fileand retry the upload procedure. If you are still unable to successfully perform the GPS Subsystem
upgrade, you should contact Customer Support at EndRun Technologies.

Performing the GPS Receiver UpgradeThis section has instructions for upgrading the GPS Receiver. If you want to upgrade the GPS Subsystem see the section above called Performing the GPS Subsystem Upgrade.
First you need to download the GPS Receiver firmware from the EndRun website to a place on yournetwork which is accessible to the Meridian II. The link to the Meridian II upgrade page is shown
above.
You may transfer the file to your Meridian II using either ftp or scp. If you are using ftp to
perform the upgrade, transfer the previously downloaded file using binary transfer mode from theremote host to this specific file on your Meridian II: /tmp/rcvr.bin. The GPS Receiver image will be
named with the software part number and version like: 6010-0081-000_1.04.bin. When following
the instructions below, substitute the name of the actual GPS Receiver image that you are installingfor 6010-0081-000_1.04.bin. You will be transferring the file to a temporary file, /tmp/rcvr.bin on
your Meridian II.
ftp remote_host{perform ftp login on remote host}bin{set transfer mode to binary}get 6010-0081-000_1.04.bin /tmp/rcvr.bin {transfer the file}quit{close the ftp session after the transfer }If you are using SSH to perform the GPS Receiver upgrade, you may open another command window
on the remote computer and securely transfer the GPS Receiver image to /tmp/rcvr.bin using scp
from the remote computer. A command like this could be used:
scp –p 6010-0081-000_1.04.bin root@host.your.domain:/tmp/rcvr.bin

Now issue the following command to the Meridian II console to initiate the upload:

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upgradercvr

This command performs the file transfer to the GPS Receiver. You will see a file transfer progressmessage while it is performing the transfer. Next, issue the following command to the Meridian II
console to reset the GPS Subsystem (and Receiver):subsysreset

After it completes, wait about 60 seconds and issue this command to check the GPS Receiver version:
rcvrversion

You should see a message like this:F/W 6010-0081-000 Ver 1.04 - FPGA 6020-0014-000 Ver 01 - JAN 28 13:08:52 2013

The firmware version should match that of the binary file that you uploaded.
Problems with the GPS Receiver Upgrade
Should you have difficulties with the upgrade due to a corrupt file, power failure during upload, orother accident, do not be alarmed. Even though you may have lost the existing application program,the GPS Receiver bootloader program will remain intact. Correct any problem with the binary fileand retry the upload procedure. If you are still unable to successfully perform the GPS Receiverupgrade, you should contact Customer Support at EndRun Technologies.

Performing the GPS Receiver FPGA UpgradeThis section has instructions for upgrading the Field-Programmable Gate Array (FPGA) resident on
the GPS Receiver. This is rarely, if ever, used. Therefore, it’s not an option on the HTTPS interface.
First you need to download the FPGA image from the EndRun website to a place on your network
which is accessible to the Meridian II. The link to the Meridian II upgrade page is shown above.
You may transfer the file to your Meridian II using either ftp or scp. If you are using ftp to perform the upgrade, transfer the previously downloaded file using binary transfer mode from the remote
host to this specific file on your Meridian II: /tmp/rcvrfpga.rbf. The FPGA image will be named with
the image part number and version like: 6020-0014-000_02.rbf. When following the instructions below, substitute the name of the actual FPGA image that you are installing for 6020-0014-000_02.rbf.
You will be transferring the file to a temporary file, /tmp/rcvrfpga.rbf on your Meridian II.
ftp remote_host{perform ftp login on remote host}bin{set transfer mode to binary}get 6020-0014-000_02.rbf /tmp/rcvrfpga.rbf{transfer the file}quit{close the ftp session after the transfer }If you are using SSH to perform the GPS Receiver upgrade, you may open another command window
on the remote computer and securely transfer the FPGA image to /tmp/fpga.bin using scp from theremote computer. A command like this could be used:
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scp –p 6020-0014-000_02.rbf root@host.your.domain:/tmp/rcvrfpga.rbf

Now issue the following command to the Meridian II console to initiate the upload:
upgradercvrfpga

This command performs the file transfer to the FPGA on the GPS Receiver. You will see a file transfer progress message while it is performing the transfer. Next, issue the following command to the
Meridian II console to reset the GPS Subsystem (and Receiver):subsysreset

After it completes, wait about 60 seconds and issue this command to check the FPGA version on the
GPS Receiver:rcvrversion

You should see a message like this:F/W 6010-0081-000 Ver 1.04 - FPGA 6020-0014-000 Ver 02 - OCT 11 13:08:52 2015

The FPGA version should match that of the binary file that you uploaded.

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Appendix C

Helpful Linux Information
You do not need knowledge of Linux commands in order to operate Meridian II. All commands necessary for proper operation are described in Chapter 3 - Console Port Control and Status. However, the Meridian II does support a subset of the standard Linux commands and utilities and it uses
the bash shell, which is the Linux standard, full-featured shell. Very brief descriptions of some of themost useful Linux information is described in this appendix.

Linux Users

Meridian II is shipped from the factory with two users enabled. The first is the “root” user withpassword “endrun_1”. The root user has access to everything on the system, including the ability toperform system setup procedures.
The other user is “sysuser” with password “Praecis”. When logged in as sysuser you may checkstatus information and view log files but you will not be able to modify any system settings or view
secure files.
For security reasons, we recommend you change the default passwords using the Linux passwd command (see Change Password below).

Linux Commands

Detailed Information Is Available

A very brief description of the most helpful Linux commands and utilities is listed in this appendix.
On Linux systems, the system commands are located in the directories with “bin” in their name, e.g.
/usr/bin or /sbin. You can list the contents of those directories using the ls command to see what is
installed on your Meridian II. Then you can find out about those commands using the man command,
which stands for “manual”. For example, to read details on the ps command type this:man ps

A very detailed description, called a “man page”, of the ps command will be shown. To navigate
in the document, press `d’ to scroll down, `b’ to scroll up, and `q’ to quit and return to the commandprompt.
To search the database of man pages, use either apropos or whatis. apropos will do partial word
searches, while whatis will only find matching whole words. For example to find all man pages
dealing with ntp:
apropos ntp

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The relevant available man pages are shown:
ntp []
ntpd []
ntpdc []
ntpq []
ntpsnmpd []sntp []

(1)
(1)
(1)
(1)
(1)
(1)

- keygen - Create a NTP host key- NTP daemon program- vendor-specific NTP query program- standard NTP query program- NTP SNMP MIB agent- standard SNTP program

Now you can issue issue man commands on each of these man pages to find what you are looking for.

Change Password

This command is used to change the password for the user that you are logged in as. It affects theserial port, SSH, Telnet and HTTPS.
passwdList Active Processes

This command displays all active processes running in the system.
ps -e

NTP Monitoring and Troubleshooting

The following command displays which NTP clients are reaching the NTP daemon running on the
Meridian II. It will not try to look up host names.
ntpq -n -c mrulist

A useful command for querying NTP status is the following.
ntpq -peers

To query a remote time server (if the remote timeserver will accept the query) type:ntpq -peers <hostname>

A table of information will be displayed. For details on what each of the table columns means type:
man ntpq

To see what version of the NTP daemon, ntpd, is operating type:ntpd --version

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Text Editors

There are three text editors resident on the Meridian II file system: edit, joe and elvis. All ofthese may be useful when needing to edit system configuration files or to view and search within
system log files.
is the recommended editor for all purpose use in configuring and monitoring the
Meridian II. It is a full-featured editor with syntax highlighting and is also based on the Wordstar
commands. It is user friendly with easy to find help for its key commands, and complete man page
documentation. It is started by simply issuing the command joe [file-to-edit], optionallywith a file name to edit. It is the modern replacement for edit (see below).
joe

is a very simple editor with Wordstar key commands that was originally developed for
extremely memory-limited environments, such as floppy boot disks and embedded Linux appliances.
When EndRun Technologies’ first generation Linux-based embedded network time servers wereintroduced, they fell into this category and the edit text editor was appropriate. Now it is included
on the Meridian II file system for legacy reasons, since it has been the default editor for all first andsecond generation EndRun Technologies products. A man page for edit is resident on the system.
When it is first started, and you did not give it a file name to edit on the command line, it shows astart-up screen with its command syntax, But once you have opened a file to edit, online help is notavailable. It is started by issuing the command edit [file-to-edit], optionally with a file nameto edit.
edit

is a full-featured vi clone which is provided in the Meridian II file system for masochistic Unix diehards. It is not the least bit user friendly to anyone lacking experience with text modeapplications. If you don’t know what vi is, avoid using this editor! It is started by simply issuing thecommand vi [file-to-edit], optionally with a file name to edit.
elvis

Change Log-In
Banners

There are three different log-in banners in the Meridian II - the serial port banner, the Telnet banner,and the SSH banner. You must be logged in as the “root” user in order to edit the rc.local file andchange the log-in banners. Perform the following:
edit /etc/rc.d/rc.local

Change the banners as appropriate. After saving the file, copy it to /boot/etc like this:cp -p /etc/rc.d/rc.local /boot/etc/rc.dThen reboot for your changes to take effect.

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Query and Change
Ethernet Ports

ethtool is a Linux utility that allows you to query or change the settings for Port 0 (eth0) and Port
1 (eth1). For example, to view current settings for Port 0 issue the following command:
ethtool eth0

Here is an example of one way to set the speed on Port 0 to 1000Base-T:
ethtool -s eth0 speed 1000 duplex full autoneg off

The command above will immediately change the port speed to 1000Base-T, but it will revert to its
factory (10/100/1000Base-T) at a system reset. If you want to retain the setting after a system reset,
then you need to edit the rc.M configuration file. Follow this sequence:
1. Edit /etc/rc.d/rc.M using one of the editors on the previous page.
Insert the desired ethtool line (see example above) after the Gatekeeper Daemon is started andbefore the Precision Time Protocol is started. Exit and save the rc.M file.
2. Now you need to copy the rc.M file into a location that will ensure your changes persist
through a system reset. Copy /etc/rc.d/rc.M to /boot/etc/rc.d as shown:
cp /etc/rc.d/rc.M /boot/etc/rc.d

For more details on ethtool and how to use it type:man ethtool

Redirect Syslog Files
to Remote Host

You can redirect syslog files to a remote host (syslog server) by adding the standard Linux redirectcommands to the Meridian II’s syslog.conf file. Follow this sequence:
1. Edit /etc/syslog.conf using one of the editors on the previous page. Insert this line:*.* @remote_host

Substitute the actual name or IP address of your remote syslog server for “remote_host”. The
most common log file to be directed to the Syslog Server is the messages.log file which contains
authenticated user login activity. If you would like to only redirect this log info to the remote
host, insert this line instead of the one above:messages.log @remote_host

Exit and save the syslog.conf file.
2. Now you need to copy the syslog.conf file into a location that will ensure your changes persist
through a system reset. Copy /etc/syslog.conf to /boot/etc/syslog.conf as shown:
cp /etc/syslog.conf /boot/etc/syslog.conf

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Appendix D

Third-Party Software
The Meridian II is running several different software products created and/or maintained by open
source projects. Open source software comes with its own license. These are printed out for yourinformation below.
The license for the GNU software project requires that we provide you with a copy of all source code
covered under the GNU Public License (GPL) at your request. Please contact us with your request
and we will mail it to you on a CD. We will charge you a fee for our incurred expenses as allowed
for in the license.

GNU General
Public License

Everyone is permitted to copy and distribute verbatim copies of this license document, but changing
it is not allowed.
Preamble
Copyright © 2007 Free Software Foundation, Inc. ( fsf.org )The GNU General Public License is a free, copyleft license for software and other kinds of works.
The licenses for most software and other practical works are designed to take away your freedom toshare and change the works. By contrast, the GNU General Public License is intended to guarantee
your freedom to share and change all versions of a program--to make sure it remains free software forall its users. We, the Free Software Foundation, use the GNU General Public License for most of oursoftware; it applies also to any other work released this way by its authors. You can apply it to yourprograms, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses
are designed to make sure that you have the freedom to distribute copies of free software (and charge
for them if you wish), that you receive source code or can get it if you want it, that you can change
the software or use pieces of it in new free programs, and that you know you can do these things.
To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software,or if you modify it: responsibilities to respect the freedom of others.

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For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass onto the recipients the same freedoms that you received. You must make sure that they, too, receive or
can get the source code. And you must show them these terms so they know their rights.
Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.
For the developers’ and authors’ protection, the GPL clearly explains that there is no warranty for thisfree software. For both users’ and authors’ sake, the GPL requires that modified versions be marked
as changed, so that their problems will not be attributed erroneously to authors of previous versions.
Some devices are designed to deny users access to install or run modified versions of the software
inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim ofprotecting users’ freedom to change the software. The systematic pattern of such abuse occurs in thearea of products for individuals to use, which is precisely where it is most unacceptable. Therefore,
we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains infuture versions of the GPL, as needed to protect the freedom of users.
Finally, every program is threatened constantly by software patents. States should not allow patents torestrict development and use of software on general-purpose computers, but in those that do, we wish
to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.

NTP
Software License

Information about the NTP Project can be found at: ntp.org. The distribution and usage of the NTP
software is allowed, as long as the following copyright notice is included in our documentation. For
more information see: opensource.org/licenses/ntp-license.php****************************************************************************** Copyright (c) University of Delaware 1992-2015**** Permission to use, copy, modify, and distribute this software and** its documentation for any purpose with or without fee is hereby** granted, provided that the above copyright notice appears in all** copies and that both the copyright notice and this permission** notice appear in supporting documentation, and that the name*
* University of Delaware not be used in advertising or publicity** pertaining to distribution of the software without specific,** written prior permission. The University of Delaware makes no** representations about the suitability this software for any** purpose. It is provided “as is” without express or implied** warranty.
******************************************************************************
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T H I R D - PA RT Y S O F T WA R E****************************************************************************** Copyright (c) Network Time Foundation 2011-2015**** All Rights Reserved**** Redistribution and use in source and binary forms, with or without** modification, are permitted provided that the following conditions** are met:*
* 1. Redistributions of source code must retain the above copyright** notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above** copyright notice, this list of conditions and the following** disclaimer in the documentation and/or other materials provided** with the distribution.
**** THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS’’ AND ANY EXPRESS ** OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED ** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR** PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,** STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)** ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
****************************************************************************

Apache Software License

Copyright [2013] [EndRun Technologies]
Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at: apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions andlimitations under the License.

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The PTP/IEEE-1588 option as implemented in the Meridian II is covered by patents and copyrights.
For patents that pertain to the Std No 1588, see the IEEE Standards Association.
Information about the PTP Project, led by Kendall Correll, can be found at:
ptpd.sourceforge.net
The distribution and usage of the PTP software is allowed, as long as the following copyright notice
is included in our documentation. The copyright notice applies to all files which compose the PTPd.
This notice applies as if the text was explicitly included in each file.
Copyright (c) 2005-2008 Kendall Correll, Aidan Williams
Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee
is hereby granted, provided that the above copyright notice and this permission notice appear in all
copies.
THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGESWHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

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Appendix E

Installing the GPS AntennaThis appendix contains guidelines for installing the GPS antenna. Mounting the antenna with a goodview-of-the-sky is very important. A rooftop installation is usually best. The accuracy & stability
specifications in Appendix K - Specifications assume an antenna installation with a very good viewof-the-sky.

Antenna Location

The location of the antenna must be chosen based on having as clear a view of the sky as possible.
Any obstructions such as buildings, large metal objects or other antennas, and even trees, will limit
the performance of the GPS antenna. The antenna should also be located away from overhead powerlines or circuits, for safety reasons. The illustration below shows some examples of good and badantenna mounting locations.

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GPS Antenna Kit

The Meridian II typically ships with a GPS Antenna Kit which includes 50 feet (15 meters) of antenna cable. This amount of cable is sufficient for the majority of GPS antenna installations. Longer
cable runs can also be accommodated. Figure 1 shows the GPS antenna rooftop mounting hardware.
Below is a list of the items in a typical GPS Antenna Kit, part number 0610-0009-001:• GPS Antenna (part #0502-0013-000)• Mounting Pipe (part #0602-0060-018)• Two Hose Clamps (part #0100-0008-000)• 50 feet of RG-59U (Belden 9104) Cable/TNC Male (part #0600-0013-050)**• A GPS Rooftop Installation Guide (part #5050-0017-000).
** NOTE: If you will not be using the EndRun-supplied cable, then please read the section below
called Recommended Cable.

About Coax Cable

The GPS signal frequency is considered to be in the microwave range and is highly affected by
impedance mismatches and discontinuities in the transmission cables. All RF coax cables have aminimum bend radius. In order to prevent damage, cable should not be bent into tight curves. It is
critically important during installation that kinks are not allowed to form in the cable. If RF coax
cable is bent beyond its minimum bend radius. then damage to the inner construction of the cable
may result. This can lead to much higher levels of loss and a non-functioning GPS receiver.
Similarly, care should be taken to ensure that the cable is not crushed, or likely to be crushed later. If
the RF coax cable does suffer this kind of damage, then the dimensions of the cable will be changed
and it will not maintain its characteristic impedance. Again, this can result in a non-functioning GPS
receiver.

IMPORTANT
Care must be taken when installing the GPS cable. Do not treat it like a power extension cord or garden
hose. Please:
Do not allow kinks to form in the cable at any time.
Ensure that the cable is not crushed at any time.
Do not bend the cable into tight curves.
Ignoring these precautions may damage the cable and cause a myriad of GPS reception problems.

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I N S TA L L I N G T H E G P S A N T E N N ALong Cable Runs

Most devices are installed with only 50 feet (15 meters) of antenna cable. However, there are many
circumstances where 50 feet is inadequate. We can accommodate cable lengths up to 1000 feet using
a combination of low-loss cable and preamplifiers.

Recommended Cable

The factory-supplied GPS cable is an RG-59 type. RG-59 is a broad classification, with wide variation in performance between cables from different manufacturers and for different applications. We
supply two specific cables: Belden 9104 or Belden 1505A. Belden 9104 is constructed with a copperplated steel center conductor and an aluminum outer braid. Belden 1505A is constructedof all solid copper conductors. Both cables are double shielded, low-loss cables designed forthe cable TV industry, and they both have a signal loss of 10 dB/100 feet at GPS frequencies. The
Belden 1505A also has very low DC resistance, which is important for long cable runs. For very longcables, if the DC resistance is too high, not enough voltage will be available at the end farthest from
the Meridian II where the antenna and preamplifiers are installed. For cable lengths less than 700
feet, Belden 9104 is acceptable.

IMPORTANT
If you are supplying the cable for your GPS installation, then you must make sure the cable you install iscomparable to the Belden 9104 or Belden 1505A. Specifically, the cable must:
Be double-shielded
Have 10 dB or less of loss per 100 feet at 1.5 GHz.
Have very low DC resistance (for cable lengths > 700 feet)
Choosing an inferior cable type can cause a myriad of GPS reception problems.

Using GPS Low-Noise Amplifiers (LNAs)

For longer cable lengths, you will need one or more LNAs (see chart below). We produce the
G-LNA2 which is a very high-performance, low-noise, low-power drain, inline amplifier for difficult
GPS signal environments and long cable runs (greater than 250 feet of factory-supplied cable). The
following table shows the number of LNAs we recommend for each GPS antenna installation using
our factory-supplied cable. Installations using other cable types may have different preamplifer
requirements.

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Cable Length

Cable
Type

Number of
LNAs

Up to 250 feet
(76 meters)
251 to 500 feet
(77 to 152 meters)
501 to 700 feet(153 to 213 meters)
701 to 750 feet(214 to 228 meters)
751 to 1000 feet(229 to 305 meters)

Belden 9104
or equivalent
Belden 9104
or equivalent
Belden 9104
or equivalent
Belden 1505A
or equivalent
Belden 1505A
or equivalent

0
1
2
2
3

An Installation Guide for installing a rooftop-mounted antenna and a GPS preamplifer is shown at theend of this appendix in Figures 1 and 2.
Using Two or Three LNAs
Installation for one LNA is simple. But the physical layout of two or three LNAs is critical. An improper installation can cause feedback from the output of the last LNA, through the cable shield andback up to the antenna. This highlights the importance of properly constructed cable terminations
and double shielded cable.

IMPORTANT
Proper installation of two or three LNAs is critical:
Use the appropriate cable as specified in the previous section Long Cable Runs.
Ensure properly constructed cable terminations.
LNAs must be installed in a straight line down from the bottom of the antenna (no bends or loops).
An improper installation may create problems for your GPS receiver and any antennas nearby.

For installations using three preamps, we recommend that the last pre-amp be located as far as ispractical from the antenna. This is because the antenna and three preamplifers will have more than
100 dB of gain, increasing the likelihood that enough leakage from the cable can cause “round-theworld” feedback to the antenna and set up oscillation. Here is the suggested configuration for anantenna installation with two or three preamplifiers:

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Other Accessories

Two LNAs

Three LNAs

GPS Antenna
One-foot cable
LNA
One-foot cable
LNA
Up to 750 feet (228 meters) of cable
Meridian II Precision TimeBase

GPS Antenna
One-foot cable
LNA
One-foot cable
LNA
Up to 1000 feet (305 meters) of cable
LNA
One-foot cable
Meridian II Precision TimeBase

Lightning Arrestor

A lightning arrestor helps protect your GPS installation from damage due to lightning strikes. It is
designed to pass the DC voltage that is needed to power the antenna and/or preamps without degrading the GPS signal. It is installed between the antenna and the receiver where the cable enters thebuilding, near an earth-ground. You must bond the lightning arrestor to the earth-ground.

Signal Splitters

Signal splitters are used when two GPS receivers are sharing one antenna installation. The smart
GPS Splitter supplied by EndRun is a one-input, two-output device. In the normal configuration, oneof the splitter RF outputs (J1) passes DC from the connected GPS Receiver through the splitter to theantenna, allowing the GPS Receiver to power both the antenna and the splitter amplifier. The otherRF output (J2) is DC loaded with a 200-ohm resistor to simulate the antenna current draw.
When selecting and installing a signal splitter keep these points in mind:
1. The splitter must be DC-blocked on one leg. The GPS Receiver in EndRun’s products provide+5 VDC up the coax to power the GPS antenna’s built-in preamp. The two GPS receivers connectedto the splitter outputs must not have their power sources connected together.
2. It is desirable that the DC-blocked leg has a DC load resistor to simulate a GPS antenna load.
This way you will not get a false alarm from the GPS Receiver’s antenna load sensor. However, theMeridian II allows you to mask an antenna fault alarm from causing a system fault by using the setantfltmask command. See details in Chapter 3 - Console Port Control and Status.
3. The signal splitter supplied by EndRun has a built-in preamplifier to compensate for signal loss
through the splitter. If using a splitter other than the one supplied by EndRun you may need to compensate for splitter signal loss by using a separate GPS preamplifier.

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Calibrate Your Receiver

In order for the Meridian II to synchronize with maximum accuracy to UTC, the delay for the cableand all devices between the antenna and the GPS receiver input (i.e. GPS preamplifiers, signal splitters, lightning arrestors, etc.) must be compensated for. You can do this via the keypad/display (seeChapter 13 - Front-Panel Keypad/Display, Receiver: Calibrate) or via the console port caldelay
and setcaldelay commands (see Chapter 3 - Console Port Control & Status).
Calibration is used to compensate for the propagation delay between the GPS antenna and the Meridian II GPS receiver input connector. Positive values remove delay by advancing Meridian II’s 1 PPS
on-time reference by the specified number of nanoseconds. Negative values add delay by retarding
the 1 PPS and are used in special circumstances. The calibration value is determined by summing all
the delays.
The calibration range is ±500,000 nanoseconds. The default value as shipped from the factory is 0.
The table below lists nominal propagation delays for the GPS cable and accessories supplied by
EndRun Technologies. For the most demanding timing applications, it is recommended that the delay
between the antenna and Meridian II receiver input be precisely measured.

EndRun Part #Description

Nominal Delay

Notes

Antenna Cable
0610-0009-001

Kit with 50’ (15m) cable62 nanoseconds

Belden 9104, 1.24 ns/foot0600-0013-050

50’ (15m) cable62 nanoseconds

Belden 9104, 1.24 ns/foot0600-0013-100

100’ (30m) cable

124 nanoseconds

Belden 9104, 1.24 ns/foot0600-0013-150

150’ (46m) cable

186 nanoseconds

Belden 9104, 1.24 ns/foot0600-0013-200

200’ (61m) cable

248 nanoseconds

Belden 9104, 1.24 ns/foot0600-0013-250

250’ (76m) cable

310 nanoseconds

Belden 9104, 1.24 ns/foot0600-0060-800

800’ (244m) cable

992 nanoseconds

Belden 1505A, 1.24 ns/foot1000’ (304m) cable

1240 nanoseconds

Belden 1505A, 1.24 ns/foot0600-0060-A00

GPS Low-Noise Amplifier
3509-0001-000

G-LNA220 nanoseconds

See device label for exact delay.

4011-0002-000

G-LNA2 Kit(with 1’ cable)

21 nanoseconds

See device label for exact delay
and add 1.24 ns for the 1’ cable.

0502-0009-000

Lightning Arrestor<1 nanosecond

0502-0011-000

GPS Signal Splitter<1 nanosecond

Fiber Optic Link
3430-0003-000
3430-0004-000
3430-0005-000

178Fiber Optic Receiver
Fiber Optic Transmitter
Fiber Optic Transmitter17 nanosecondsperReceiver/Transmitterpair.

Add the delay of single mode
fiber optic cable which istypically 1.4/1.5 ns/foot.
See cable specification.

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I N S TA L L I N G T H E G P S A N T E N N A

Mounting On
A Rooftop

Mounting your GPS antenna with an unobstructed view of the sky (usually on a rooftop) is therecommended installation. Please follow these guidelines to eliminate exposure to electrical service
wiring and to minimize the potential for lightning strikes.

Installations subject to lightning strikes should use a lightning arrestor installed at the building entrance. A lightning arrestor suited for this purpose is available through EndRun Technologies. The
arrestor must be installed according to the manufacturer’s instructions.

Do NOT route the antenna wiring near or with AC wiring (Class 1 circuits per the NEC). Do NOT
mount the antenna wiring where it may become energized by nearby AC wiring or components
should they fall.

Obtaining A
Reference Position

About WGS-84
HeightYour Meridian II is capable of operation from either an automatically determined GPS reference
position or a manually entered GPS reference position. If you need to provide a reference position
to your Meridian II, it is best to use a previously determined position from the unit itself or a highly
accurate surveyed position.

Internally, GPS receivers report latitude, longitude and height above the WGS-84 ellipsoid. However, for a lot of reasons, WGS-84 is not the way that mapmakers and surveyers report the height. Thatmeans, in order to use the height information as reported by Meridian II, you need to do a conversion.
One easy way to do the conversion is by going to this link:unavco.org/software/geodetic-utilities/geoid-height-calculator/geoid-height-calculator.html

After entering your latitude and longitude, this website will give you a report showing the GPS ellipsoidal height, the Geoid height, and the Orthometric height. The Orthometric height is the one mostpeople are familiar with, which is height above mean sea level. However, GPS receivers use the GPS
ellipsoidal height. Below is a sample report:
GPS ellipsoidal height = 0 (meters)
Geoid height = -31.023 (meters)
Orthometric height (height above mean sea level) = 31.023 (meters)

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Appendix F
Leap Seconds

UTC stands for Coordinated Universal Time. UTC is the international time standard most commonlyused in the world and by the Network Time Protocol (NTP). A leap second insertion is scheduled
about every one-and-a-half to three years in order to keep UTC in alignment with the Earth’s rotation. Possible leap second insertions can be scheduled at 23:59:59 UTC on June 30 or December 31.

Automatic
Leap Second Insertion

Your GPS-synchronized Meridian II precisely adjusts for leap seconds if and when they occur. Thereis nothing you need to do in order to keep your Meridian II time server accurately synchronized toUTC.
You can see the current GPS-UTC parameters that are downloaded from the satellites by using the
gpsutcinfo command. See Chapter 3 - Console Port Control and Status for details on this command or type help gpsutcinfo at the console port.

Background Information

Leap seconds are inserted from time-to-time in order to keep UTC, which is derived from atomic
time (TAI), in agreement with the Earth’s rotation rate. Relative to TAI, the Earth’s rotation rate isslowing down. This means that UTC must be retarded periodically in order to maintain agreement
between UTC and the apparent daylength. If this were not done, eventually UTC would drift out-ofsync with Earth’s day and many astronomical and navigational problems would ensue.
The International Earth Rotation and Reference Systems Service (IERS) is the organization responsible for measuring the relationship between UTC and the rotation rate of the Earth. When the difference between UTC and apparent Earth time has exceeded a certain threshold, the IERS coordinateswith the Bureau International of the Hour (BIH) to schedule the insertion of a leap second into the
UTC time scale. The IERS publishes Bulletin C about 6 months in advance of each possible leap
second insertion point. Bulletin C confirms whether a leap second will or will not be inserted at thenext possible insertion point. The IERS website is:iers.org
EndRun summarizes this information at this link:endruntechnologies.com/support/leap-seconds

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Appendix G
System Faults

The status of the Meridian II is constantly monitored and a fault will occur when any of several
parameters is out of spec. When this happens the Alarm LED on the front panel will light. This appendix defines the various faults.

Overview

The Alarm LED will light when a fault has occurred. You can see which fault is the problem by using the faultstat command.

Masking Faults

Some faults can be masked. These are the ANT (GPS Antenna) and SIG (GPS Signal) faults. Whenmasked, these faults will not cause an alarm. You may want to mask the ANT fault if you are using a
GPS splitter. You may want to mask the SIG fault if you are operating your Meridian II as a Stratum
2 NTP Server and are not using a GPS signal. For information on Stratum 2 see Chapter 7 - NTP,
Configuring the Meridian II as a Stratum 2 Server.
To mask a fault you can use the front-panel keypad/display or a console port commands setantfltmask and setsigfltmask. For more information see Chapter 3 - Console Port Control and Status
or type help setsigfltmask and help setantfltmask on the console.
If your Meridian II has the Dual Power Supply option then you may mask primary and/or secondary
power supply faults. See Chapter 10 - Options, Masking Dual Power Supply Fault Alarms for more
information.

System Fault Definitions

System Oscillator DAC (DAC)This fault indicates that the electronic frequency control DAC for the oscillator has reached either thehigh or low alarm limit while locked to the GPS signal. Unless the unit is being subjected to out-ofspecification environmental conditions, this would indicate that the oscillator frequency has drifted
near to the end of life region. This should normally only occur after at least ten years of operation.
The unit will continue to function until the oscillator frequency finally reaches one of the actual DAC
endpoints. The unit should be returned to the factory for oscillator replacement at your convenience.
GPS Signal (SIG)
This fault indicates that the unit has not been able to acquire a GPS signal for one hour while theTime Figure of Merit has been 9, the unsynchronized condition. This could be due to a variety ofreasons. If there are no other faults that could explain the inability to receive a signal, then there
could be an antenna failure or blockage. If the condition persists indefinitely, and a problem with theantenna is not evident, then please contact EndRun Customer Support.
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GPS Subsystem FPGA Configuration (FPGA)This fault indicates that the GPS Subsystem is unable to configure the FPGA. This is a fatal fault.
Please contact EndRun Customer Support.
GPS Subsystem FLASH Writes (FLSH)
This fault indicates that the GPS Subsystem is unable to verify a write to the FLASH non-volatileparameter storage area. This should never occur under normal operation.. Please contact EndRun
Customer Support.
GPS Receiver Communication (RCVC)
This fault indicates that the GPS Subsystem is unable to establish communications with the GPS
Receiver. Please contact EndRun Customer Support.
GPS Reference Time (REF)
This fault indicates that the GPS Subsystem received an erroneous time input from the GPS Receiver.
If the condition persists please contact EndRun Customer Support.
Subsystem Communication (POLL)
This fault indicates that the GPS Subsystem is not receiving polling requests from the Linux Subsystem. This could be due to a hardware or software failure. If the condition persists please contact
EndRun Customer Support.
GPS Receiver (RCVF)
This fault indicates a problem with the GPS Receiver. See the section below (Receiver Faults) for
more information.
System Oscillator PLL (Phase-Lock-Loop)
This fault indicates that there is an unlock condition between the main system oscillator and the othersystem timebase clocks. This is a fatal fault. Please contact EndRun Customer Support.
GPS Antenna (ANT)This fault indicates that the GPS antenna or cable has a fault. It indicates either an over or under current condition. Usually it means that the antenna cable is not plugged into the connector on the rear of
the Meridian II. To see whether it is a short or an open check the receiver faults. This fault may also
occur when using an antenna signal splitter. In this case you may want to mask the fault. Use thesetantfltmask command.
Plug-In Option (OPT)This fault indicates that an unrecognized option module was plugged in the Meridian II. This may
occur if you try to install an option module from a first-generation Meridian into a Meridian II. The
Meridian and Meridian II option modules are not compatible.
System Power/Configuration (PWR)
This fault indicates misconfiguration of the Meridian II chassis which may have caused a power overload. This is a fatal fault. Please contact EndRun Customer Support.
5071A - Option
Used only when the 5071A Cesium Control Module is installed. This fault indicates a problem withthe 5071A. See Chapter 10 - Options, 5071A Cesium Control Module, Faults for information.
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Primary Power Supply (PRIPS) - Option
Used only when the Dual-Redundant Power Supplies are installed. This fault indicates that the primary power supply is not producing an output. See Chapter 10 - Options, Dual-Redundant Power
Supplies for information on the dual power supplies option.
Secondary Power Supply (SECPS) - Option
Used only when the Dual-Redundant Power Supplies are installed. This fault indicates that the secondary power supply is not producing an output.. See Chapter 10 - Options, Dual-Redundant Power
Supplies for information on the dual power supplies option.

Receiver Fault Definitions

When a fault on the GPS Receiver occurs, the system fault indicator RCVF will show fault and theAlarm LED will light. You can see which fault is the problem by using the faultstat command.
Below are details about each fault indicator.
GPS Receiver Oscillator DAC (DAC)This fault indicates that the DAC for the oscillator has reached either the high or low alarm limit
while locked to the GPS signal. Unless the unit is being subjected to out-of-specification environmental conditions, this would indicate that the oscillator frequency has drifted near to the end of life
region. This should normally only occur after at least ten years of operation. The unit will continue
to function until the oscillator frequency finally reaches the DAC endpoint. The unit should be returned to the factory for oscillator replacement at your convenience.
GPS Signal (SIG)
This fault indicates that the GPS Receiver has not been able to acquire a GPS signal for one hourwhile the Time Figure of Merit has been 9, the unsynchronized condition. This could be due to avariety of reasons. If there are no other faults that could explain the inability to receive a signal, thenthere could be an antenna failure or blockage. If the condition persists indefinitely, and a problem
with the antenna is not evident, then please contact EndRun Customer Support.
GPS Receiver FPGA Configuration (FPGA)This fault indicates that the GPS Receiver is unable to configure the FPGA. This is a fatal fault.
Please contact EndRun Customer Support.
GPS Receiver FLASH Writes (FLSH)
This fault indicates that the GPS Receiver is unable to verify a write to the FLASH non-volatileparameter storage area. This should not ever occur under normal operation.. Please contact EndRun
Customer Support.
Synthesizer Limits (SYN1)This fault indicates that the local oscillator synthesizer has reached the alarm limit. This condition
should not normally occur unless the unit is subjected to out-of-specification environmental conditions. Otherwise, this is a fatal fault. Please contact EndRun Customer Support.
Synthesizer (SYN2)This fault indicates that the local oscillator synthesizer has failed. This condition should not normally occur unless the unit is subjected to out-of-specification environmental conditions. Otherwise,
this is a fatal fault. Please contact EndRun Customer Support.
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GPS Reference Time (REF)
This fault indicates that the GPS Receiver received an erroneous time input from the GPS signals. If
the condition persists please contact EndRun Customer Support.
GPS Receiver Oscillator (OSC)This fault indicates that the main oscillator has failed. This is a fatal fault. Please contact EndRun
Customer Support.
Antenna Short (SHRT)This fault indicates that the GPS antenna has an overcurrent condition (short).
Antenna Open (OPEN)
This fault indicates that the GPS antenna has an undercurrent condition (open).
GPS Receiver Oscillator PLL (Phase-Lock-Loop)
This fault indicates that there is an unlock condition between the receiver oscillator and the othersystem timebase clocks. This is a fatal fault. Please contact EndRun Customer Support.

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Appendix H
Time Code Formats

A standard feature of your Meridian II Precision TimeBase is a single time code output available
at the rear panel BNC connector identified as AM CODE. A DC-shift time code is available as an
optional output on the CPU Module (see CPU Module Options in Chapter 10 - Optional Rear-Panel
Outputs). Multiple time code outputs (both AM and DC-shift) are also available via an option board
module (see Plug-In Module Options in Chapter 10).
The output code format is selectable via the front-panel user interface. See Time Code Output Setup
in Chapter 13 - Front-Panel Keypad and Display. You can also select the time code format via a
console command. See CpuOptsConfig in Chapter 3 - Control and Status Commands. Each format
is described below. Time codes are commonly used to provide time information to external devices
such as displays, magnetic tape devices, strip chart recorders and several types of embedded computer peripheral cards.
IRIG-B122/002
This is the most widely used format and is normally the factory default for the AM Code output. The
IRIG-B122 format is a 100 bps code and is used to amplitude modulate a 1000 kHz sine wave carrier.
The information contained in the time code is seconds through day-of-year coded in Binary Coded
Decimal (BCD). Reference IRIG Document 200-004.
IRIG-B123/003
In addition to the time information identified in B122 above, this format also contains Straight Binary
Seconds (SBS) of day. SBS is provided at the end of the frame, in the 17 bits starting in position 80.
IRIG-B120/000 (IEEE-Standard 1344-1995)
In addition to the time data and the Straight Binary Seconds data this format provides for time/status data in the control bit positions of IRIG-B. The information provided there is defined by IEEE
standard 1344-1995: Unit and Tens of Years, Leap Second, Daylight Saving Time, Local Time Offset,
Time Quality and Parity. The IEEE-1344 table provided below shows each bit position with detailed
information.
NASA-36
NASA-36 bit time code is a 100-bit, pulse width modulated format used to amplitude modulate a1000 kHz sine wave carrier. The information contained in the time code is seconds, minutes, hours
and days. The format is used by several military ranges. Reference IRIG Document 200-04.
2137
The 2137 code is a 25-bit pulse width modulated format used to amplitude modulate a 1000 kHz sine
wave carrier. The information contained in the time code is seconds, minutes and hours. The format
is used by certain security organizations.

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IEEE-1344 Bit Definition
Bit Position

Bit Definition

Explanation

P50
P51
P52
P53
P54
P55
P56
P57
P58
P59
P60
P61
P62
P63
P64
P65
P66
P67
P68
P69
P70
P71
P72
P73
P74
P75
P76-P78
P79

Year, BCD1
Year, BCD2
Year, BCD4
Year, BCD8
Not usedYear, BCD10
Year, BCD20
Year, BCD40
Year, BCD80
P6Leap second pending
Leap second
Daylight Saving Time pending
Daylight Saving Time
Local offset sign
Local offset binary 1
Local offset binary 2
Local offset binary 4
Local offset binary 8
P7
Local offset half hour bit
Time quality binary 1
Time quality binary 2
Time quality binary 4
Time quality binary 8
ParityNot used
P8

Unit years

* 0
4
5
6
7
8
9
F

Tens years

Position identifier
Set to one, 59 seconds prior to leap insertion
0 = add second, 1 = delete second
Set to one, 1 second prior to DST change
1 = DST active
0 = +, 1 = Local offset from UTC time

Position identifier
0 = none, 1 = half hour time offset added
Time quality indicates clock precision.*

Odd parity for all preceding data bits
Position identifier

normal operation, clock locked (TFOM = 3)time error is < 1 us
time error is < 10 ustime error is < 100 ustime error is < 1 mstime error is < 10 mstime error is > 10 mstime not reliable, never locked to GPS

Refer to Appendix A - Time Figure-of-Merit for detailed information on TFOM and time error.

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Appendix I
Software Options

Your Meridian II supports software options. These are the Real-Time-Ionospheric-Corrections
Option described in Chapter 11 - RTIC, the Precision Time Protocol described in Chapter 9 - PTP/
IEEE-1588 and Synchronous Ethernet described in Chapter 12 - SyncE. This appendix is about
viewing or enabling software options, using the PTP Option in the examples below.
Normally, EndRun products are configured from the factory with software options enabled. But
software options are also field-installable. In other words, you can enable a software option yourself,
after you have received your Meridian II. First you must obtain an 8-digit license key from EndRun
Technologies, then you can enable it using the wrt_sw_opt command.

wrt_sw_opt
To enable a software option use this console port command. You must be logged in as the root user
in order to run this command and you must provide a license key on the command line. If the key isverified, then the option will be enabled.
Command:
Sonoma reply:

wrt_sw_opt [key]Option to be enabled is PTP0 Daemon

installed_sw_opts
This user-friendly command shows which software options are enabled in your Sonoma. Below is an
example when PTP is installed on both ports.:
Command:
Sonoma reply:

installed_sw_opts
The PTP0 Daemon Option is Installed.
The PTP1 Daemon Option is Installed.

Another example is below, no software options are installed:
Command:
Sonoma reply:

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get_sw_opts
This command is documented here for completeness. The installed_sw_options command
above is much easier to use. The get_sw_opts command returns a 32-bit value with each bit identifying a software option. Below is an example when no software options are enabled:

Command:
Sonoma reply:

get_sw_opts
00000000000000000000000000000000

Bit are numbered from 0 to 31, from right to left. The example below shows bit 0 set which identifies
that the PTP0 option is enabled.
Command:
Sonoma reply:

get_sw_opts
00000000000000000000000000000001

Software Option Bit Definitions
Bits are numbered from 0 to 31, from right to left. Currently, there are only three software options
defined in the Meridian. These are for the SyncE Option, the RTIC Option and PTP/IEEE-1588
enabled on port 0 (eth0) or port 1 (eth1). The table below shows the currently defined bits.
Bit 31

192

Bit 30.......

Bit 6

Bit 5

Bit 4
SyncE
Port 1(eth1)Bit 3
SyncE
Port 0(eth0)

Bit 2
RTIC

Bit 1
PTP
Port 1(eth1)

Bit 0
PTP
Port 0(eth0)

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Appendix J

Operation with a GPS Simulator
This appendix describes several commands that are intended for use before and after operation witha GPS simulator. In addition, recommendations for the simulator setup are given so that the advanced integrity-checking and GPS week number ambiguity resolution algorithms operating in the
GPS Subsystem will not cause unexpected behaviors during and after running on the simulator.

Background

Console Port Commands

GPS-based timing systems supporting critical infrastructure functions could be vulnerable to malfunction due to weak signals, jamming, spoofing or accidental GPS control system errors. EndRun
Technologies’ GPS timing receiver technology has evolved to be highly robust against these threats.
Because of this, operation with a GPS simulator requires careful attention when setting up the simulator. Careful consideration must also be given in configuring the GPS Subsystem before and after
simulator operation. Failure to understand and implement the information that follows could result in
confusing simulation results and/or improper operation when the Meridian II is subsequently reconnected to live GPS signals.

clearalmanac

The GPS Subsystem maintains a record of the GPS almanac data received from the satellites in its
non-volatile memory. These almanacs are used to calculate the elevations and doppler frequency
offsets of GPS satellites so that they may be more quickly acquired and tracked by the signal processor. When operating on a GPS simulator, any previously stored almanacs gathered from the live GPS
may not contain valid data, so they should be cleared prior to operation with a simulator. Likewise,
following operation with a simulator, they should also be cleared before reconnecting to live GPS
signals. The clearalmanac command provides this capability.
This command clears all GPS almanac data from both non-volatile and working memory in the GPS
Subsystem. (It does not clear the copy of the Yuma-formatted almanac that is retrieved with the
dumpalmanac command. That data will be updated on reception of new almanac data.)
The clearalmanac command can be used at other times, but is typically used before and after operation with a GPS simulator.

SUMMARY
The clearalmanac command MUST be executed both before and after use with a GPS simulator.

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Command:clearalmanac
MeridianII reply: Clearing GPS Almanacs

resetlastgpswn

The GPS Subsystem is designed to autonomously handle future rollovers of the 10-bit GPS weeknumber received in data from the satellites. To do that, it maintains a record in non-volatile memoryof the unambiguous, full GPS week number when it was last locked to the GPS system, i.e. the Last
GPS Week Number. If this information is not available, then the full GPS week number corresponding to the build date of the GPS receiver firmware will be used as the Last GPS Week Number.
This Last GPS Week Number is the minimum possible full GPS week number. The Meridian II will
never allow the date and time to be set prior to the date and time corresponding to this Last GPS
Week Number. For example, setting the simulator time to a date two weeks in the past will result in
the Meridian II setting the date 1022 weeks in the future.
This means that a simulator should not be set to a date in the past. Doing so will cause the time tobe set a multiple of 1024 weeks in the future relative to the simulator time. If lock to the simulator
is then achieved, this future time will then be saved to non-volatile memory as the Last GPS Week
Number. Subsequent runs with the simulation time set in the past would cause this time to continue
to advance.
Following simulator operation, it is imperative that the non-volatile Last GPS Week Number be resetto the firmware build date. This is accomplished by running the resetlastgpswn command prior
to reconnecting to live GPS signals.

SUMMARY
The simulator should not be set to a date in the past.
You MUST disconnect the antenna or simulator from the Meridian II and then execute the resetlastgpswn command before reconnecting the Meridian II to a live GPS signal.
IMPORTANTThis command should not be used unless you have reason to believe that operation with a GPS simulator
has previously taken place. Arbitrary usage of this command could compromise the effectiveness of thealgorithm in autonomously handling the GPS week number rollover events.
The command must be issued with one argument: TRUE
Command:resetlastgpswn TRUE
MeridianII reply: Resetting Last GPS Week Number

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resetleaphistory

The GPS Subsystem performs extensive integrity/sanity checking on the data received from the GPS
satellites. In particular, the current and future UTC leap second values received in the almanac data
are compared to a historical record of previous UTC leap seconds and the GPS week numbers at
which they were inserted into the UTC timescale. Should a simulator be set with arbitrary values forthese UTC leap seconds that differ by more than a couple of seconds from the actual values currently
being transmitted by the GPS, the almanac data will be rejected.
The simulator should be set with realistic UTC leap second values. If the simulator is set with incorrect UTC leap second values, yet they are close enough to pass the integrity screen, then they will be
accepted and it will be necessary to run the resetleaphistory command prior to reconnecting tolive GPS signals. Failure to do so would compromise the integrity checking algorithm.
Issuing this command will reset the stored GPS Leap Second History to the history that was correct atthe build date of the receiver firmware. As long as the firmware build date is not too many years old,
this will allow the receiver to operate properly when it receives signals from the actual GPS satellites.

SUMMARY
The simulator should be set with realistic UTC leap second values, such as those currently being transmitted
by GPS.
If you simulate a leap second insertion then you MUST execute the resetleaphistory command
before reconnecting the receiver to a live GPS signal.
IMPORTANTThis command should not be used unless you have reason to believe that operation with a GPS simulator
has previously taken place. Arbitrary usage of this command could cause important leap history events tobe lost. This will compromise the effectiveness of the integrity checking algorithm.
The command must be issued with one argument: TRUE
Command:resetleaphistory TRUE
MeridianII reply: Resetting Leap History

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Appendix K
Specifications

The following accuracy and stability specifications assume a stationary position (not dynamic mode),four satellite lock, and the antenna mounted with a full view-of-the-sky.

GPS Receiver:L1 Band – 1575.42 MHz.
12 Channels, C/A Code (16 correlators).
Static mode and dynamic-platform mode (shipboard only).
15 dB minimum gain at receiver input.
Timing Receiver Autonomous Integrity Monitoring (TRAIM).
TNC connector (female) on rear panel, Zin = 50Ω, 5 VDC to antenna.

GPS Antenna Kit (Option):

Antenna
TNC jack on rear panel, Zin = 50Ω, antenna power = +5V.
Integral +40 dB gain LNA with bandpass filter for out-of-band interference rejection.
Rugged, all-weather housing capable of operation over –40°C to +85°C.
MTBF: 163,441 hours at 70° C.
Size: 3.25”H x 3.0” diameter.
Mounting via 18” long, 3⁄4” PVC pipe with stainless steel clamps.
50’ low-loss RG-59 downlead cable is typical cable length.
Extension cables and low noise pre-amplifiers are available.

Time to Lock:< 5 minutes, typical (TCXO).
< 10 minutes, typical (OCXO/Rb).
< 30 minutes, typical (Cesium).

Timing Characteristics:

Accuracy: < 10 nanoseconds RMS to UTC(USNO) when locked.*
Stability: TDEV < 10 ns, τ < 105 seconds, σy(τ) < 6.0x10-14 @ τ=105 secs.
Stability: TDEV < 2 ns, τ < 105 seconds, σy(τ) < 4.0x10-14 @ τ=105 secs with the RTIC Option.
See Chapter 11 - Real-Time Ionospheric Corrections, Specifications.
User-Calibration: +/- 500 us, 1 ns resolution.
*See GPS-UTC Timing Specifications for details.

Platform:

Operating System Kernel Version: 3.2.2
Slackware Linux Distribution: 14.2
Processor: 1.2 GHz.
RAM: 512M
FLASH: 512M

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Alphanumeric Display/Keypad:

Display: Brilliant 16x280 graphical dot-matrix vacuum-fluorescent.
Keypad: Enter, Back, Edit, Right, Left, Up, Down, Help.

System Status LEDs:

Sync LED: Amber LED pulses to indicate GPS acquisition and lock status.
Alarm LED: Red LED indicates a fault condition.

Network I/O:

Two rear-panel RJ-45 jacks.
10/100/1000Base-T Ethernet.
Two LEDs on each port indicate speed and activity.
Amber LED indicates activity.
Green LED indicates speed (1 pulse = 10M, 2 pulses = 100M, 3 pulses = 1G).

NTP Server Performance:

ΝTP Timestamp Accuracy: <10 microseconds @ 7500 requests/second.

Supported IPv4 Protocols:

SNTP, NTP v2, v3, v4, SHA/MD5 authentication, broadcast/multicast and autokey
SSH client and server with “secure copy” utility, SCP
SNMP v1, v2c, v3 with Enterprise MIB
TIME and DAYTIME server
TELNET client/server
FTP client
DHCP client
SYSLOGHTTPS
PTP/IEEE-1588 ((See the Software Options section in this Appendix K.)
SyncE (See the Software Options section in this Appendix K.)

Supported IPv6 Protocols:

SNTP, NTP v2, v3, v4, SHA/MD5 authentication, broadcast/multicast and autokey
SSH client and server with “secure copy” utility, SCP
SNMP v1, v2c, v3 with Enterprise MIB
TIME and DAYTIME server
HTTPS
Note: See Chapter 8 - IPv6 Information for more details.

Serial Port I/O:

Signal: I/O port at RS-232 levels for secure, local terminal access.
Parameters: 19200 baud, 8 data bits, no parity, 1 stop bit.
Connector: Rear-panel DB-9M connector labeled “RS-232”.
To connect to a computer, a null-modem adapter must be used. The serial cable provided with the
shipment is wired as a null-modem. Pinout for the RS-232 console port is shown below.
Note: For operational details see Chapter 3 - Console Port Control and Status.

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Meridian II DB9M Pin
1
2
3
4
5
6
7
8
9

Signal Name
Not Connected
Receive Data (RX)Transmit Data (TX)
Not Connected
GroundNot Connected
Not Connected
Not Connected
Not Connected

1 PPS Output:

Signal: Positive TTL pulse into 50Ω.
TTL (50Ω to GND): VOL(max)=0.4V, VOH(min)=2.4V, VOH(nom)=2.5V, VOH(max)=3.0V.
Width: User selectable to 20 us, 1 ms, 100 ms, 500 ms.
User-Calibration: +/- 500 us, 1 ns resolution.
Accuracy: < 10 nanoseconds RMS to UTC(USNO) when locked.*
Stability: TDEV < 10 ns, τ < 105 seconds, σy(τ) < 6.0x10-14 @ τ=105 secs.
For RTIC Option see Chapter 11 - Real-Time Ionospheric Corrections, Specifications.
Rise Time: < 2 nanoseconds.
Αlignment: Within 5 ns of the other TTL outputs in this unit (except the optional DDS).
Connector: Rear-panel BNC jack on CPU Module labeled “1PPS”.
Note: To change the pulse width refer to Chapter 10 - Rear-Panel I/O, 1PPS Output.
*See GPS-UTC Timing Specifications for details.

AM Code Output:

Signal: Amplitude-modulated (AM), 3:1 ratio, 1 kHz carrier.
Drive: 1 VRMS into 50Ω.
Format: User selectable to IRIG-B (120/IEEE-1344/C37.118-2005, 122, 123), NASA-36, 2137.
Alignment: Within 5 us of 1 PPS.
Connector: Rear-panel BNC jack on CPU Module labeled “AMCODE”.
Note: To change the time code format refer to Chapter 10 - Rear-Panel I/O, Time Code Output.

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Size:

1U Chassis (AC power):
1U Chassis (DC power):
1U Weight:
2U Chassis (AC power):
2U Chassis (DC power):
2U Weight:
Antenna:

Environmental:

Operating Temperature:
Storage Temperature:
Antenna Operating Temperature:
Operating Humidity:
Storage Humidity:
Maximum Operating Altitude:1.75”H x 17.15”W x 11.2”D. 19” rackmount.
1.75”H x 17.15”W x 11.8”D. 19” rackmount.
< 8 lb. (3.6 kg.)
3.5”H x 17.15”W x 11.2”D. 19” rackmount.
3.5”H x 17.15”W x 11.8”D. 19” rackmount.
< 13 lb. (5.9 kg.)3.25” H x 3” Diameter.
0° to +50° C-40° to +85° C-40° to +85° C
5% to 90% RH, non-condensing.
5% to 95% RH, non-condensing.
AC:
13,125 ft. / 4000 meters.
12/24 VDC:
13,125 ft. / 4000 meters.
48 VDC (<61 VDC Max.): 13,125 ft. / 4000 meters.
48 VDC (>60 VDC Max): 6,562 ft. / 2000 meters.
125 VDC:6,562 ft. / 2000 meters.

Chassis Power (1U):

Warmup:10-50W, depending on options.
Operating:10-35W, depending on options and ambient temperature.
90-264 VAC, 47-63 Hz, 1.0A Max; 0.8A Max @ 120 VAC/60 Hz; 0.5A Max @ 240 VAC/50 Hz.
3-Pin IEC 320 on rear panel, 2 meter line cord is included.

Chassis Power (2U):

Warmup:10-90W, depending on options.
Operating:
10-40W, depending on options and ambient temperature.
90-264 VAC, 47-63 Hz, 1.5A Max; 1.3A Max @ 120 VAC/60Hz; 0.7A Max @ 240 VAC/50 Hz.
3-Pin IEC 320 on rear panel, 2 meter line cord is included.

Software Options

Optional Real-Time Ionospheric Corrections (RTIC):
Specifications are listed in Chapter 11 - RTIC.

Optional PTP/IEEE-1588 Grandmaster:IEEE-1588-2008 (v2) with hardware timestamping.
Version 2 Parameters: Default Profile. Multicast or Hybrid (mixed Unicast/Multicast). Two-Step
Clock.
Delay Mechanism: E2E or P2P. Delay Interval: 32 seconds. Transport: UDP/IPv4.
Sync Interval: 1, 2, 4, 8, 16, 32, 64 or 128 packets / 1 second.
Announce Interval: 1 packet per 1, 2, 4, 8 or 16 seconds.
PTP Timestamp Resolution: 8 nanoseconds.
PTP Timestamp Accuracy to Reference Clock: 8 nanoseconds.
Note: See Chapter 9 - PTP/IEEE-1588 for more information.

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Optional SyncE:

Synchronous Ethernet in Meridian II meets the specifications defined in the ITU-T:
G.8261 Architecture and wander performance
G.8262 Timing characteristics
G.8264 Ethernet Synchronization Message Channel (ESMC)
Note: See Chapter 12 - Synchronous Ethernet for more information.

System Oscillator

TCXO:
Temp Stability: 2.5x10-6 over -20º to 70º C. Ageing Rate/Year: 1x10-6.
NTP Stratum 1 Holdover: 24 hours.
Optional Medium-Stability OCXO (MS-OCXO):
Temp Stability: 4x10-9 over 0º to 70º C, Ageing Rate/Year: 3x10-8.
NTP Stratum 1 Holdover: 35 days.
Optional High-Stability OCXO (HS-OCXO):
Temp Stability: 1x10-9 over 0º to 70º C. Ageing Rate/Year: 3x10-8.
NTP Stratum 1 Holdover: 35 days.
Optional Ultra-Stable OCXO (US-OCXO):
Temp Stability: 5x10-10 over 0º to 70º C. Ageing Rate/Year: 3x10-8.
NTP Stratum 1 Holdover: 35 days.
Optional Ultra-Stable Rubidium (US-Rb) - available in 2U only:
Temp Stability: 2x10-10 over -20º to 65º C. Ageing Rate/Year: 5x10-10.
NTP Stratum 1 Holdover: 400 days
Optional 5071A Cesium Control Module (Cs):
Temp Stability: 1x10-13 for all environmental effects. Ageing Rate/Year: 0.
NTP Stratum 1 Holdover: 1,000,000 days
Optional 5071A Cesium Control Module with High-Performance Beam Tube (HP-Cs):
Temp Stability: 1x10-13 for all environmental effects. Ageing Rate/Year: 0.
NTP Stratum 1 Holdover: 1,000,000 days

System Oscillator Stability and Phase Noise on next page.

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System Oscillator Stability (Allan Deviation) Table (@ 10 MHz):
Tau in Seconds
TCXO*
MS-OCXO*
HS-OCXO*
1
2.0x10-10
3.0x10-12
1.0x10-12
-10
-12
10
2.0x103.9x101.3x10-12
-11
-12
100
8.0x103.0x101.7x10-12
-12
-12
1000
8.0x102.0x101.5x10-12
-13
-13
10000
8.0x104.0x104.0x10-13-14-141000006.0x106.0x106.0x10-14
Tau in Seconds
1
10
100
1000
10000
1000001000000

US-Rb*
1.5x10-11
5.0x10-12
1.4x10-12
7.0x10-13
4.0x10-13
6.0x10-14

Cs**
1.2x10-11
8.5x10-12
2.7x10-12
8.5x10-13
2.7x10-13
8.5x10-14
1.0x10-14

US-OCXO*
4.0x10-13
5.0x10-13
8.5x10-13
8.0x10-13
4.0x10-13
6.0x10-14

HP-Cs**
5.0x10-12
3.5x10-12
8.5x10-13
2.7x10-13
8.5x10-14
2.7x10-14
1.0x10-14* For stability specifications with RTIC Option see
Chapter 11 - Real-Time Ionospheric Corrections, Specifications.
** 5071 Cesium Control Module specifications are stated above with RTIC Option included.
System Oscillator Phase Noise Table (dBc/Hz @ 10 MHz):
Hz
TCXO
Spurs
1
-70
10
-100
-100
100
-125
-100
1k
-135
-100
10k
-140
-100
100k
-145
-120
Ηz
1
10
100
1k
10k
100k

MS-OCXO
-95
-120
-135
-145
-145
-145

HS-OCXO
-105
-130
-140
-150
-150
-150

US-OCXO
-113
-138
-148
-152
-153
-153

Spurs

Ηz
1
10
100
1k
10k
100k

US-Rb
-92
-130
-145
-150
-153
-153

Cs
-85
-125
-135
-140
-145
-145

HP-Cs
-100
-130
-135
-140
-145
-145

Spurs

-120
-115
-125
-125
-110

-120
-115
-125
-125
-110

System Oscillator 5 MHz Phase Noise on next page.

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System Oscillator Phase Noise Table (dBc/Hz @ 5 MHz):Ηz
MS-OCXO
HS-OCXO
US-OCXO
1
-100
-110
-118
10
-130
-135
-143
100
-140
-145
-152
1k
-150
-155
-155
10k
-150
-155
-155
100k
-150
-155
-155

US-Rb
-92
-130
-135
-135
-135
-135

Phase Noise for TCXO is typical. Phase Noise for all other oscillators is typical on the Sine Wave Module and guaranteed on Low-Phase-Noise Module.

Power Supply Options

Optional DC Power Input (1U):

12 VDC (10-20 VDC), 6.0A maximum.
24 VDC (19-36 VDC), 3.0A maximum.
48 VDC (37-76 VDC), 2.0A maximum.
125 VDC (70-160 VDC), 1.0A maximum.
3-position terminal block on rear panel: +DC IN, SAFETY GROUND, -DC IN(Floating power input: Either “+” or “-” can be connected to earth ground.)Note: For more information see Chapter 10 - Rear-Panel I/O, DC Power Input.

Optional DC Power Input (2U):

24 VDC (19-36 VDC), 4.0A maximum.
48 VDC (37-76 VDC), 2.0A maximum.
3-position terminal block on rear panel: +DC IN, SAFETY GROUND, -DC IN(Floating power input: Either “+” or “-” can be connected to earth ground.)Note: For more information see Chapter 10 - Rear-Panel I/O, DC Power Input.

Optional Dual-Redundant Power Supplies:

Any combination of Universal AC and/or DC supplies.
Note: For more information see Chapter 10 - Rear-Panel I/O, Dual-Redundant Power Supplies.

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CPU Module Options

Optional 1 PPS (RS-422) Output (CPU Module):

Signal: RS-422 levels.
RS-422 (100Ω differential): VDIFF(min)=2.1V, VDIFF(nom)=2.4V, VDIFF(max)=3.0V,
VOUT(max)=3.3V referenced to GND.
User-Selectable Width: 20 us, 1 ms, 100 ms, 500 ms.
User Calibration: +/- 500 us, 1 ns resolution.
Accuracy: <10 nanoseconds RMS to UTC(USNO) when locked.*
Stability: TDEV < 10 ns @ τ < 105 seconds, σy(τ) < 6.0x10-14 @ τ=105 secs.
Rise Time: < 3 nanoseconds.
Αlignment: Within 5 ns of the TTL outputs in this unit (except the optional DDS).
Connector : Rear-panel DB-9M connector labeled “1PPS RS-422”.
Pinout: Pin 3 is +signal. Pin 6 is -signal. Pin 5 is GND.
Note: To change the pulse width refer to Chapter 10 - Rear-Panel I/O, 1PPS Output.
*See GPS-UTC Timing Specifications for details.

Optional DC Code Output (CPU Module):

Signal: Positive TTL pulse into 50Ω (DC Level Shift) or RS-422.
TTL (50Ω to GND): VOL(max)=0.4V, VOH(min)=2.4V, VOH(nom)=2.5V, VOH(max)=3.0V.
RS-422 (100Ω differential): VDIFF(min) = 2.1V, VDIFF(Nom) = 2.4V, VDIFF(max) = 3.0V,
VOUT(max) = 3.3V referenced to GND.
Format: User selectable to IRIG-B (000/IEEE-1344/C37.118-2005, 002, 003), NASA-36, 2137.
Rise Time: < 2 nanoseconds (TTL). <3 nanoseconds (RS-422).
Alignment: Within 5 ns of the other TTL outputs in this unit (except the optional DDS).
Connector: Rear-panel BNC jack labeled “DCCODE”.
Note: To change the format refer to Chapter 10 - Rear-Panel I/O, Time Code Output.

Optional Programmable Pulse Output (PPO) (CPU Module):

Signal: Positive TTL pulse into 50Ω or RS-422.
TTL (50Ω to GND): VOL(max)=0.4V, VOH(min)=2.4V, VOH(nom)=2.5V, VOH(max)=3.0V.
RS-422 (100Ω differential): VDIFF(min)=2.1V, VDIFF(nom)=2.4V, VDIFF(max)=3.0V,
VOUT(max)=3.3V referenced to GND.
Rate: User selectable to 1, 10, 100, 1k, 10k, 100k, 1M, 5M, 10M PPS, 1PPM, 1PP2S, Inv1PPS*.
Accuracy: < 6x10-14 to UTC for 100k second averaging times when locked.
Stability: TDEV < 10 ns @ τ < 105 seconds, σy(τ) < 6.0x10-14 @ τ=105 secs.
Duty Cycle: 50% except 1PPS which mimics the standard 1PPS Output defined above.
Rise Time: < 2 nanoseconds (TTL). < 3 nanoseconds (RS-422).
Alignment: Within 5 ns of the other TTL outputs in this unit (except DDS, if any).
Connector: Rear-panel BNC jack labeled “PPO”.
Note: To change the selection or to use the TriggerPPO function, refer to Chapter 10 - Rear-Panel
I/O, Programmable Pulse Output (PPO) Option.
*Inverted 1PPS (falling edge on-time) available in 1U and 2U.

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Optional Direct Digital Synthesizer (DDS) Output (CPU Module):

Signal: Positive TTL pulse into 50Ω or RS-422.
TTL (50Ω to GND): VOL(max)=0.4V, VOH(min)=2.4V, VOH(nom)=2.5V, VOH(max)=3.0V.
RS-422 (100Ω differential): VDIFF(min)=2.1V, VDIFF(nom)=2.4V, VDIFF(max)=3.0V,
VOUT(max)=3.3V referenced to GND.
Rate: User selectable 1 PPS to 10MPPS in 1PPS steps (per system DDS setting).
Accuracy: < 6x10-14 to UTC for 100k second averaging times when locked.
Rise Time: < 2 nanoseconds (TTL). < 3 nanoseconds (RS-422).
Alignment: DDS rates are NOT aligned with the other pulse rates in this unit.
Connector: Rear-panel BNC jack labeled “DDS”.
Note: To change the selection refer to Chapter 10 - Rear-Panel I/O, Direct Digital Synthesizer.

Optional 10 MPPS Rate Output (CPU Module):

Signal: Positive TTL pulse into 50Ω or RS-422.
TTL (50Ω to GND): VOL(max)=0.4V, VOH(min)=2.4V, VOH(nom)=2.5V, VOH(max)=3.0V.
RS-422 (100Ω differential): VDIFF(min)=2.1V, VDIFF(nom)=2.4V, VDIFF(max)=3.0V,
VOUT(max)=3.3V referenced to GND.
Rate: An on-time 10 MPPS pulse rate.
Accuracy: < 6x10-14 to UTC for 100k second averaging times when locked.
Stability: TDEV < 10 ns @ τ < 105 seconds, σy(τ) < 6.0x10-14 @ τ=105 secs.
Rise Time: < 2 nanoseconds (TTL). < 3 nanoseconds (RS-422).
Alignment: Within 5 ns of the other TTL outputs in this unit (except DDS, if any).
Connector: Rear-panel BNC jack labeled “10MPPS”.
Note: For more information refer to Chapter 10 - Rear-Panel I/O, 10 MPPS Output Option.

Optional Alarm Output (CPU Module):

Signal: MMBT2222A open collector, grounded emitter. High impedance in alarm state.
Voltage: 40 VDC, maximum.
Saturation Current: 100 mA, maximum.
Connector: Rear-panel BNC jack or terminal block labeled “ALARM”.
Pinout (terminal block): Pins 1, 2, 3 are NC (not connected). Pin 4 is OC. Pin 5 is GND.
Note: For more information refer to Chapter 10 - Rear-Panel I/O, Alarm Output.

Optional Serial Time Output (CPU Module):

Signal: Output only port at RS-232 (±5V) or RS-422 levels.
RS-422 (100Ω differential): VDIFF(min)=2.1V, VDIFF(nom)=2.4V, VDIFF(max)=3.0V,
VOUT(max)=3.3V referenced to GND.
Baud Rate: User Selectable to 4800, 9600, 19200 or 57600.
Parity: User Selectable to Odd, Even or None.
ASCII Formats: User-Selectable to Sysplex, EndRun, EndRunX, Truetime, NENA or NMEA.
Accuracy: The “on-time” characters starts transmitting within the first 20 microsecs of each second.
Connector (RS-232): Rear-panel DB-9M connector labeled “SERIAL TIME”.
Pinout (RS-232): Pin 3 is Transmit Data. Pin 5 is GND.
Connector (RS-422): Rear-panel DB-9M connector labeled “SERIAL TIME (RS-422)”.
Pinout (RS-422): Pin 3 is +signal. Pin 6 is -signal. Pin 5 is GND.
Note: For more information refer to Chapter 10 - Rear-Panel I/O, Serial Time Output.

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Plug-In Module Options

Optional Low Phase Noise Module:

Quantity: 4 outputs (1U or 2U chassis) or 6 outputs (2U chassis only).
Οutput Frequency: 5 MHz or 10 MHz.
Οutput Level: +13 dBm, +/- 2 dBm at 50Ω.
Harmonics: < -45 dBc at 50Ω.
Channel-to-Channel Isolation: > 75 dB
Stability: See System Oscillator Stability (Allan Deviation) Table above.
Phase Noise: See System Oscillator Phase Noise Table above.
Alignment: Not aligned with other outputs in this unit.
Connector: Rear-panel BNC jack.
Note: See Chapter 10 - Rear-Panel I/O, Low Phase Noise Module for more information.

Optional 5071A Cesium Control Module:

Quantity: 4 outputs (uses 2 slots).
Οutput Frequency: 1 MHz, 5 MHz or 10 MHz.
Οutput Level: +13 dBm, +/- 2 dBm at 50Ω.
Harmonics: < -45 dBc at 50Ω.
Channel-to-Channel Isolation: > 75 dB
Stability: See System Oscillator Stability (Allan Deviation) Table above.
Phase Noise: See System Oscillator Phase Noise Table above.
Alignment: Not aligned with other outputs in this unit.
Connector: Rear-panel BNC jack.
Note: See Chapter 10 - Rear-Panel I/O, 5071A Cesium Control Module for more information.

Optional Sine Wave Module:

Quantity: 4 outputs (1U or 2U chassis) or 6 outputs (2U chassis only).
Οutput Frequency: 1 MHz, 5 MHz or 10 MHz.
Οutput Level: +13 dBm, +/- 2 dBm at 50Ω.
Harmonics: < -45 dBc (< -40 dBc with TCXO).
Stability: See System Oscillator Stability (Allan Deviation) Table above.
Alignment: Not aligned with other outputs in this unit.
Connector: Rear-panel BNC jack.
Note: See Chapter 10 - Rear-Panel I/O, Sine Wave Module for more information.

Optional Direct Digital Synthesizer (DDS) Sine Wave Module:

Quantity: 4 outputs.
Οutput Frequency: 1 - 10 MHz (per system DDS setting).
Accuracy: < 6x10-14 to UTC for 100k second averaging times when locked.
Οutput Level: +13 dBm, +/- 2 dBm at 50Ω.
Alignment: Not aligned with other outputs in this unit.
Connector: Rear-panel BNC jack.
Note: See Chapter 10 - Rear-Panel I/O, DDS Sine Wave Module for more information.

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Optional Analog Time Code Output Module:

Quantity: 4 outputs.
Drive: 1 VRMS into 50Ω.
Frequency: 1 kHz.
Alignment: Within 5 us of 1 PPS.
User-Selectable Formats: IRIG-B (122, 123, IEEE-1344 compliant), NASA-36, and 2137.
Connector: Rear-panel BNC jack.
Note: See Chapter 10 - Rear-Panel I/O, Analog Time Code Output Module for more information.

Optional Digital Output Module:

Quantity: 4 outputs.
Signal: TTL into 50Ω, RS-232 or RS-422 (RS-422 available in 1U chassis only).
TTL (50Ω to GND): VOL(max)=0.2V, VOH(min)=2.8V, VOH(nominal)=3.0V, VOH(max)=3.3V.
RS-232: +/- 5V into 3kΩ; Slew Rate: 30 V/us.
RS-422 (100Ω differential): VDIFF(min) = 2.1V, VDIFF(Nom) = 2.4V, VDIFF(max) = 3.2V,
VOUT(max) = 3.5V referenced to GND.
Type of output: Programmable Pulse Output (PPO), Time Code, Direct Digital Synthesizer (DDS) ora preset rate, such as a 10MPPS. Output types are described below.
Rise Time: < 2 nanoseconds (TTL). < 3 nanoseconds (RS-422).
Connector (TTL): Rear-panel BNC jack.
Connector (RS-232/RS-422): Rear-panel DB9M.
Pinout (RS-232): Pin 1 is Output A, Pin 2 is Output B, Pin 3 is Output C, Pin 4 is Output D.
Pinout (RS-422): Pin 1 is Output A+, Pin 2 is Output B+, Pin 3 is Output C+, Pin 4 is Output D+,
Pin 5 is Ground, Pin 6 is Output A-, Pin 7 is Output B-, Pin 8 is Output C-,
Pin 9 is Output D-.
Note: See Chapter 10 - Rear-Panel I/O, Digital Output Module for more information.
Programmable Pulse Output:
Rate: User selectable to 1, 10, 100, 1K, 10K, 100K, 1M, 5M, 10M PPS, 1PPM, 1PP2S, Inv1PPS*
Duty Cycle: 50% except 1PPS that mimics the width of the standard 1PPS Output and
1PP2S and 1PPM that are 1 second wide.
Alignment: Within 5 ns of the other TTL outputs in this unit (except the optional DDS).
Stability: TDEV < 10 ns, τ < 105 seconds, σy(τ) < 6.0x10-14 @ τ=105 secs.
Alignment (TTL/RS-422): Within 5 ns of the other TTL outputs in this unit (except DDS, if any).
Alignment (RS-232): The actual realized alignment is a function of the zero-crossing delay as
specified above (primarily due to the RS232 slew rate limit) and the actual receiver detection
threshold. The alignment of synthesized rate pulses remains fixed following each system
initialization, but its relationship to other pulse outputs is non-deterministic.
*Inverted 1PPS (Falling edge on-time) is not available in the 2U.
Digital Time Code (DC-Level Shift):
Format: User-selectable, IRIG-B (002, 003, IEEE-1344 compliant), NASA-36, or 2137.
Alignment (TTL/RS-422): Within 5 ns of the other TTL outputs in this unit (except DDS, if any).
Alignment (RS-232): See Alignment (RS-232) above.
Direct Digital Synthesizer (DDS):
Rate: User-selectable, 1 PPS to 10 MPPS in 1 PPS steps (per system DDS setting).
Duty Cycle: 50%.
Accuracy: < 6x10-14 to UTC for 100k second averaging times when locked.
Alignment: DDS rates are NOT aligned with the other pulse rates in this unit.

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1 PPS or 10 MPPS Pulse Rates:
Rate: Factory preset to a pulse rate of 1 PPS or 10 MPPS.
Duty Cycle: 50% except for the 1PPS which mimics the standard 1PPS Output.
Stability: TDEV < 10 ns, τ < 105 seconds, σy(τ) < 6.0x10-14 @ τ=105 secs.
Alignment: Within 5 ns of the other TTL outputs in this unit (except DDS, if any).

Optional Telecom Clock Module:

Note: See Chapter 10 - Rear-Panel I/O, Telecom Clock Module for more information.
Composite Clock:
Quantity: 0, 1 or 2.
Type: Transformer-coupled complementary-pair via 2xRJ48C. Single-ended via 2xBNC.
Frequency: 64 kbps.
Synchronization: Phase locked to the Meridian II TimeBase 10 MHz.
Data Format: All ones. User-selectable bipolar violation (BPV).
Line Z: 110Ω nominal (complementary pair), or 75Ω nominal (single-ended).
Pulse Shape: Conforms to ITU-T G.703.
Pulse Amplitude: 3.4V pk into 133Ω, 3.0V pk into 110Ω, 2.4V pk into 75Ω.
MTIE/Jitter/Wander: Conforms to ITU-T G.811/G.823.
Line Code: Bipolar Return To Zero, Alternate Mark Inversion (AMI), 5/8 Duty Cycle.
User-selectable for 64kcc AMI with no BPV, 64kcc AMI with 8 kHz BPV,
or 64kcc with 8 kHz BPV and missing BPV at 400 Hz.
Alarm Code: User-selectable for BPV off (AIS) at Major (Blue) Alarm, or BPV always on.
All zeros (LoS) at Critical (Red) Alarm.
Connector: RJ-45 style modular jack (RJ48C-compatible), 1 per output,
or BNC (single-ended) or DB9M.
RJ48C Pinout: Pin 4 is Clock Out Ring (-). Pin 5 is Clock Out Tip (+).
DB9M Pinout: Pins 1, 5, 7 and 8 are Ground. Pin 2 is Clock Out Ring A (-). Pin 3 is No Connect.
Pin 4 is Clock Out Ring B (-). Pin 6 is Clock Out Tip A (+). Pin 9 is Clock Out Tip B (+).
E1 Clock Output:
Quantity: 0, 1 or 2.
Type: Transformer-coupled complementary-pair via 2xRJ48c or 1xDB9M. Single-ended via 2xBNC.
Frequency: 2.048 Mbps.
Synchronization: Phase locked to the Meridian II TimeBase 10 MHz.
Data Format: All ones. User-selectable for Unframed, Double-frame or CRC4 Multi-frame.
Line Z: 120Ω nominal (complementary pair), or 75Ω nominal (single-ended).
Pulse Shape: Conforms to ITU-T G.703.
Pulse Amplitude: 3.0V pk into 120Ω, 2.2V pk into 75Ω.
MTIE/Jitter/Wander: Conforms to ITU-T G.811/G.823.
Line Code: Bipolar Return To Zero, Alternate Mark Inversion (AMI)(Identical to HDB3 for all ones data.)
Alarm Code: User-selectable for Alarm Indication Signal (AIS),
or Status Sync Messaging (SSM) on Sa4 through Sa8, or none at Major (Blue) Alarm.
All zeros (LoS) at Critical (Red) Alarm.
Connector: RJ-45 style modular jack (RJ48C-compatible), 1 per output,
or BNC (single-ended) or DB9M.
RJ48C Pinout: Pin 4 is Clock Out Ring (-). Pin 5 is Clock Out Tip (+).
DB9M Pinout: Pins 1, 5, 7 and 8 are Ground. Pin 2 is Clock Out Ring A (-). Pin 3 is No Connect.
Pin 4 is Clock Out Ring B (-). Pin 6 is Clock Out Tip A (+). Pin 9 is Clock Out Tip B (+).

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T1 Clock Output:
Quantity: 0, 1 or 2.
Type: Transformer-coupled complementary-pair.
Frequency: 1.544 Mbps.
Synchronization: Phase locked to the Meridian II TimeBase 10 MHz.
Data Format: All ones. User-selectable for Unframed, D4 SuperFrame (SF)or CRC6 Extended SuperFrame (ESF).
Line Z: 100Ω nominal.
Pulse Shape: Conforms to ITU-T G.703.
Pulse Amplitude: 3.0V pk.
MTIE/Jitter/Wander: Conforms to ANSI T1 101 and ITU-T G.811/G.824.
Line Build-Out: User-selectable for short haul (DSX-1 0-655 ft.
Line Code: Bipolar Return To Zero, Alternate Mark Inversion (AMI)(Identical to B8ZS or PDE with all ones data.)
Alarm Code: User-selectable for Alarm Indication Signal (AIS),
or Status Sync Messaging (SSM), or none at Major (Blue) Alarm.
All zeros (LoS) at Critical (Red) Alarm.
Connector: RJ-45 style modular jack (RJ48C-compatible), 1 per output, or DB9M.
RJ48C Pinout: Pin 4 is Clock Out Ring (-). Pin 5 is Clock Out Tip (+).
DB9M Pinout: Pins 1, 5, 7 and 8 are Ground. Pin 2 is Clock Out Ring A (-). Pin 3 is No Connect.
Pin 4 is Clock Out Ring B (-). Pin 6 is Clock Out Tip A (+). Pin 9 is Clock Out Tip B (+).

Alarm Relay Outputs:
Quantity: 0 or 3.
Type: Form C.
Rating: 750 mA @ 42VAC/60VDC.
NC Contact: Closed for alarm-active condition.
NO Contact: Closed for alarm-inactive condition.
Minor Alarm: Active at minor clock faults.
Major Alarm: Active at major clock fault (Blue Alarm).
Critical Alarm: Active at clock operational fault (Red Alarm).
Connector: DB9 Female.
Pinout:1
Minor NC
2
Minor NO
3
Major COM
4
Critical NC
5
Critical NO
6
Minor COM
7
Major NC
8
Major NO
9
Critical COM

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Compliance

CE/FCC:
RoHS:
WEEE:

RTTE Directive 1999/5/EC

Low Voltage Directive 2006/95/EC
EMC Directive 2004/108/EC
RoHS Directive 2011/65/EC
WEEE Directive 2012/19/EC

Supplementary Compliance Data:
Safety :EMC:

EN60950-1:2006/A11:2009/A1:2010/A12:2011
EN55024:2010, EN55032:2012 +C1,
EN61000-3-2:2014, EN61000-3-3:2013
VCCI (V3/2014.04), EN301 489-3 V1.6.1
ICES-003 A, Issue 5
FCC Part 15 Subpart B Sections 15.107 and 15.109

Data subject to change.
EndRun Technologies may make changes tospecifications and product descriptionsat any time, without notice.

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Meridian II User ManualS P E C I F I C AT I O N S

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APPENDIX K

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Meridian II User Manual

"Smarter Timing Solutions"

Special Modifications

Changes for Customer Requirements
From time to time EndRun Technologies will customize the standard Meridian II Precision TimeBasefor special customer requirements. If your unit has been modified then this section will describe what
those changes are.

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"Smarter Timing Solutions"

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